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How to Use Vac-U-Lock | Doc Johnson Vac-U-Lock FAQ

How to Use Vac-U-Lock | Doc Johnson Vac-U-Lock FAQ

The Vac-U-Lock by Doc Johnson is a unique brand of strap on sex toy that has plenty to offer couples looking to spice up their sex life in style.

There are many different harness kits on the market, but very few have the vast range of options and high quality luxury that the Vac-U-Lock dildo and strap on system offers. There are many reasons that a couple would buy a Vac-U-Lock harness and a collection of compatible adult toys including the ultra realistic UR3 silicone attachments and/or vibrators.

Introduction: In this guide, I'll explore what is Vac-U-Lock, and offer step by step instructions on how to mount and remove the accessories with talc powder. I'll discuss new upgrades with Doc Johnson suction cup dildos & offer tips and advice to make your experience more enjoyable.

What Is Vac-U-Lock?

Definition: Vac-U-Lock is a strap on harness kit for couples. It features a series of attachments with a female adapter that fits onto the male adapter connected to the front of the strap-on. The system is comprised of several different items that are compatible and interchangeable. Couples can mix and match accessories to customize their own sexual desires.

Vac-U-Lock accessories include:

  • Unisex & adjustable strap on harness
  • Ultra realistic UR3 dildos
  • Vibrating & non-vibrating attachments
  • Firm rubber attachments
  • Soft jelly & silicone dildos
  • Adapter that connects to the harness with metal snaps
  • Inflatable ball with adapter
  • Talcum powder
  • Vast range of attachment sizes & dimensions

How to Mount a Vac-U-Lock Dildo

At first it will appear obvious how to mount your Vac-u-Lock dildo on the compatible harness adapter, but you'll soon realize that it has a super tight fit! This is no mistake, it is designed this way to be sure the Vac-U-Lock attachment does not rotate on the plug during sexual intercourse.

It will stay in place no matter how rough your sex play or how often you walk around while wearing the strap-on. Watch the accompanying video demonstration, I show the following steps in order to correctly mount the attachment. I use a UR3 penis which twists on easily because the material is very soft. You may need to use extra force if you have a firmer accessory.


  1. If the red adapter is not connected to the harness already, press it on with the 4 metal snaps.
  2. Holding the dildo upside down, sprinkle 1 tsp of talcum powder inside the hole on the bottom of the attachment.
  3. Holding the dildo sideways, insert your finger into the hole and twist it around to spread the powder evenly inside the hole.
  4. Do not return the dildo to an upright position or the talc will fall out of the hole!
  5. With the dildo sideways, twist it back and forth onto the adapter plug slowly while maintaining even pressure as you push it on.

How to Remove a Vac-U-Lock Dildo

The video demonstration shows how to remove the attachment from the strapon plug. Before I explain the steps on how to remove the attachment, I'm assuming you've already put it on using my steps listed above. The secret is to make sure you have used talcum powder inside the hole.

If you didn't use powder, the pressure inside the 2 pieces creates a strong vacuum and it can be difficult to remove! If you did not use powder, the steps are still the same, but may be trickier to pull it off.

In my experience, the rubber toys create stronger vacuum connection than the silicone toys. It's possible to remove a silicone toy without using powder, but it's still recommended to use it because you don't want to over stress the surface of the toy by pulling on it all the time, it can eventually tear.


  1. Grab the dildo at the base, and slowly twist it as you pull away from the harness.
  2. Do not squeeze the dildo too hard at the base or it may be difficult to remove.
  3. Using consistent twisting motion is more effective that pulling it straight off, plus its gentler on the material, especially if you are using a UR3 silicone as the material is more delicate than rubber.

How to Wear the Vac-U-Lock Strap On

Before I begin, I must mention that the harness is unisex meaning men and women can wear it, but it is most commonly worn by men. How does a man wear the Vac-U-Lock strap on?

Vac-U-Lock and Plug
Vac-U-Lock open crotch strapon and red adapter plug.

If you look at the products photos, you'll see the picture of the crotchless base. There is an extra long and wide opening at the bottom of the panty style harness with more than enough room for a man's penis and testicles to hang below unimpeded, untouched and clear out of the way from the action happening above and the harness material to the side.

As such, this is a popular choice for men with erectile dysfunction because his flaccid penis and scrotum hang freely below. If the man can get an erection, then there's plenty of space down there too. The dildo will fit higher on the pelvic bone so an erection can make it's happy appearance below the dildo.

Women who wear the strap on can enjoy a vibrator or clitoral stimulator during sexual play too, so it makes the whole experience more interactive for the couple, they can still sexually stimulate each other and tease the naughty bits even while the strap on is the body. It's one of the least restrictive products we've seen.

How to Put on the Vac-U-Lock Strapon:

  1. Attach the plug and dildo following the instructions above.
  2. Feed the waist straps through the connectors.
  3. Step into the strapon like you're putting on underwear.
  4. Pull the straps at the hips to adjust to your waist size.
  5. Position the dildo so that the flat back of the plug rests just above your pubic bone. Note: It should fit higher than a normal strap on because of the weight of the dildo & plug.
  6. Re-adjust the straps to tighten the harness firmly on your body according to this new dildo position.
  7. Tuck the rest of the straps inside the back, or you can trim them with scissors to fit your waist size specifically.

How to Use a Vac-U-Lock Harness

One of the things you may notice is that the combination of plug & dildo feels quite heavy, so as noted above, you'll want to fit the dildo higher than you would on most other strap-ons. It should sit over the pubic bone.

The most important step in how to use a Vac-U-Lock harness is to make sure you've lubricated the dildo well with water based lubricant. Regardless of the dildo materiel you've chosen either soft or hard, rubber, jelly or silicone, you'll still need lots of lubricant. Is simply makes the whole experience better and more comfortable for the receiver. Learn how much lube to use during sex before you begin!

An essential tip to mention is to never use silicone lube with the UR3 dildos because it can melt with the silicone compounds of the toy. It's always wise to choose water base lube, furthermore, it won't stain your bed sheets or the strapon material whereas silicone lube can create “oil” stains in fabric.

What are Vac-U-Lock Adapters?

Vac-U-Lock dildo and adapter
Close-up view of the adapter & dildo base.

The Vac-U-Lock adapter is the red plastic piece that attaches to the harness and holds the compatible toys in place. The strap on system has been around for decades, and the adapters have evolved over time.

Most strap on dildos simply have a rubber or metal O ring that snaps onto the harness, or sometimes they are sewn into the fabric. The advantage here is the toy stays in place without moving around. This system can withstand active sexual motion compared to more budget options available for sale.

If you purchase any toy now, it will fit with any current adapter plug, but if yours is really old (10+ years old), it may not be compatible anymore. Vac-U-Lock adapters and plugs are all compatible now as the brand has moved to improve consistency to make it easier for customers shopping online.

Some customers have asked about the tiny red probe on the front. For a newbie to the adult toy world , this may look like the completed unit with a tiny dildo for beginners, but the plug is not made for sex, it's made to hold the pieces in place. With that being said, it's absolutely possible to use the plug with your partner vaginally or anally. Creative couples have done it before!

The Vac-U-Lock adapter is a heavy duty plastic plug with a graduated, rippled shape that looks just like a butt plug. Interested in trying anal strapon sex? Yes, you CAN use the plug as a pegging toy since it is short, small and can be removed for proper cleaning!

Of course, that's not the plugs intended purpose, I'm just thinking creatively here and offering some neat ideas for creative and adventurous couples who may be interested in trying anal strap on sex.

What is Vac-U-Lock Powder?

Vac-U-Lock Powder

Vac-U-Lock powder is Doc Johnson's own brand of talcum powder specially made to use with the strapon harness system. It acts as a lubricant to assist in removal of the attachments from the harness plug. It's unscented and will not leave greasy reside.

Why use powder? As noted in the step by step instructions above that explain how to use the dildo, when the male and female adapters are connected, it creates powerful vacuum inside, so the talcum powder acts as a lubricant to make it easier to remove the dildo from the strap on.

You do not have to use Doc Johnson's own Vac-U-Lock powder; any type will do, but this one is a popular choice for couples because it does not small like baby powder. In our opinion, using talcum is an essentially important step that will prevent your accessories and the harness material itself from overstretching and tearing during repeated application and removal.

The New Doc Johnson Vac-U-Lock

Adult sex toy connoisseurs may have noticed that many Doc Johnson dildo suction cups have changed. They are no longer a continuation of the same material, now they are an entirely separate suction cup that can be removed from the dildo. Thanks to this innovation, almost all of their line is compatible with the adapter.

We think this is an absolute ingenious invention and give great kudos to Doc Johnson for this improvement because they've opened up a whole new realm of ultra realistic suction cup dildos of all sizes, colors and shapes that can be used with their strap on harness. No longer are we limited by a small handful of attachments to choose from, now virtually any Doc Johnson dildo can be connected to their plug.

At the time of this writing, they are still in the process of liquidating old stock so make sure to double check to verify if the suction cup is removable before making your purchase online if you're buying from another online sex shop.

We sell high quantities of Doc Johnson stock so we've already sold out of the old style and are currently fully stocked with this new design that can be used with your strap on. Good times ahead folks, it just got better!

10 Best Vac-U-Lock Attachments

Vac-U-Lock UR3 Realistic

UR3 Realistic

The softest and most realistic of all dildos. Vac-U-Lock UR3 Realistic has a flexible and bendable shaft that is so soft and malleable, you may need to use both hands to insert it into the vagina. It's the most popular choice for seniors who need to use a strap on for sex because of erectile dysfunction; this attachment is by far the most gentle of them all.

Ultra Skin Medium

Ultra Skin Medium & Large

A pure elegant and luxurious creation that feels just like a real penis, this is the most life like strap on attachment we've ever seen. It is actually a dildo, but as noted previously, Doc Johnson added a removable suction cup so it is compatible with the harness. It comes in 2 sizes, both close to 8 inch long, but the Ultra Skin Large size has a thicker girth whereas the Ultra Skin Medium size is slightly thinner.

Vac-U-Lock Ribbed

The Ribbed

Women who enjoy the feel of ribbed sex toys love the Vac-U-Lock Ribbed because it has smooth veins that weave their way across the entire surface. The contrast of the rounded penis head is a real erotic delight. The rubber is firm enough so that you'll notice the sensation of the rubbed surface, but soft enough to bend and feel cozy. The small 6 inch size appeals to the masses.

Vac-U-Lock Perfect

The Perfect

The most impressive feature of the Vac-U-Lock Perfect is the oversized mushroom shaped circumcised head. It's an exaggeration of anything you'd experience in real life, and is a popular feature on many different types of women's sexual toys. This one also angles back from the testicles so it stands more upright when attached to the harness. The sensually smooth rubber shaft can bend and flex slightly too.

Vac-U-Lock Natural

The Natural

If you're seeking a firm toy for hard and vigorous sex, choose the 7 inch long Vac-U-Lock Natural before anything else. It's tailor made for rough sex and the sturdy life like shaft can pound away all night long. It's heavy duty but not too large making it an excellent fetish toy for couples who want to keep the massive size at a minimum.

Vac-U-Lock Classic

The Classic

This is the traditional shape of the original Doc Johnson dildo. The Vac-U-Lock Classic with a wide blunt head is the most sought after feature offering an immediate stretch upon entry and a chunky ribbed shaft all the way through. It's considered “slightly larger than the average” and is a best selling attachment for couples who want an upgrade in size from a small attachment.

Vac U Lock Attachment Medium Large

Standard Attachment (Medium & Large)

This is the dildo that comes included in the base Vac-U-Lock system. It is available for sale separately for couples who create their own combination, but still want the standard Medium Attachment or the thicker Large Attachment to complete their own kit. In person, it looks shockingly realistic. The smooth and luxurious rubber is one of the most well made life like attachments for any strap on. Top shelf quality & feel!

Vac U Lock Kong


The huge Kong is probably one of the worlds most famous massive dildos. It's NOT for the faint of heart. He's a giant behemoth with a massive mushroom head and bulging erection shaft with life like veins and dimples; a giant dick amplified from real life. If you're a size queen or want to enjoy pure freaky sex, the Kong is your best choice. It is a whopping 9 inches long, 2 inches wide. Whoa!

Vac U Lock Ballsy Small Medium

Ballsy Small & Medium

The best attachment for first timers, the cute & perky thin ribbed shaft with adorable testicles offers a light & airy look that won't intimidate the beginner. Couples often buy both - the Ballsy Small and Ballsy Medium because they each have a different shape and stance so they feel different from each other. They are also used as beginner trainers; start with the small and work up to medium.

Vac-U-Lock Small

The Small Realistic

The smallest attachment available for sale, this friendly little fella has life like features in a tiny size that better fits petite women and seniors. The Vac-U-Lock Small stands at an angle from the scrotum, but you'll notice this points the dildo upright when attached to the harness for easier vaginal penetration. The realistic small penis head and soft premium rubber are great for comfortable hands free use.

Vac-U-Lock Harness

Vac-U-Lock Harness

None of the above is possible without purchasing the strap-on first (unless you already have a complete Vac-U-Lock system, then you can simply add one of the above pieces.) If you want to build your own kit, buy the Vac U Lock harness and choose your favorite toy to go with it. Sex, customized to your personal desires!

Click to buy Vac-U-Lock strap ons & dildos online.

Mayla Green

Mayla Green has been involved in the sex toy industry since 2004. Working behind the motto “Sex TOYS should be FUN”, Mayla provides unique tips & advice amassed from over a decade of hands on experience with adult products. She also coaches clients how to fully enjoy sexual pleasure and can be seen in major publications & magazines online.

Happily married since 2009, she knows firsthand how the sex life eventually becomes repetitive (which truthfully means boring), so if you're looking to spice things up in the bedroom, Mayla's your gal! Her literary pride & joy is covering topics for established couples needing inspiration to keep lovemaking exciting and fun.

Not in a relationship? Her other focus is teaching women how to properly handle the “little person in the canoe” to experience the best orgasms ever, no partner required! Her creative and innovative tips, techniques and advice is on par with a certified sex therapist or Sexologist, but with an extra advantage from her knowledge of the adult toy business.

View all articles published by Mayla Green exclusively for The Adult Toy Shop sex blog. Mayla Green's Linkedin profile highlights her professional background, experience and training.

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