Vac-U-Lock Knuckle Up

Vac u lock harness lovers, meet your match. The Doc Johnson Knuckle Up Vacuum Lock fits one-size-fits-all knuckle rings and works with the full Vac-U-Lock attachment library — solo or partnered. Phthalate-free, beginner-friendly, and ships discreetly. Veteran-owned and operated. Your secret is safe with us.

Weight

0.2 oz

Dimensions

5.8 × 4.5 × 1 in

Brand:

Doc Johnson

Color:

Black

Features

Harness Compatible, Phthalate Free

Audience

Couples

Size:

One Size

UPC

782421011277

Add $69.00 for FREE standard shipping

In stock

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Vac U Lock — Knuckle Up by Doc Johnson

Name: Best Vac U Lock Knuckle Grip by Doc Johnson | Discreet Toys
Brand: Doc Johnson
SKU: DJ1010-12
Price: 22.99 USD
Availability: InStock

The Vac U Lock system, now in your hands — literally.

Bring more fun and connection into your private moments together with the Doc Johnson Knuckle Up — a black, phthalate-free accessory that fits one-size knuckle rings around a standard vac u lock plug for direct, hands-on partnered play. Compatible with the entire vac u lock attachment lineup, this is purpose-built gear for couples who know exactly what they want.

Vac U Lock Features & Specifications

Four reasons the Doc Johnson Knuckle Up earns a place in your strap-on harness kit.

Universal Vac U Lock Compatibility

Fits all vac u lock attachments
Standard plug interface, no adapters needed
Expand your strap-on dildo collection freely

One-Size Knuckle Ring Fit

Knuckle rings sit below the plug
One-size-fits-all harness compatible design
Secure grip during hands-on play

Couples & LGBTQ+ Versatility

Suited for partnered and solo use
Ideal for LGBTQ+ couples exploring strap-on play
Budget-friendly next-level gear

Material & Care

Phthalate-free, non-toxic build
Wipe clean with toy cleaner after use
Store away from other materials

Vac U Lock User Guide & Play Styles

Hands-on technique: getting the most from this strap-on harness system

The Knuckle Up is designed for couples who already understand how a strap-on harness works and want direct tactile control beyond what a conventional harness delivers. Slide your fingers through the one-size knuckle rings, seat a chosen attachment onto the vac u lock plug, and you control depth, angle, and rhythm entirely by hand — making it one of the best strap on harnesses accessories for technique-driven partnered play. The phthalate-free black body stays comfortable in extended sessions. After play, wipe down with a dedicated toy cleaner to keep the interface clean for the next attachment swap. For deeper context on building out your shared toy kit, explore our Couples Pleasure pillar guide or browse the full harness-only range.

More Strap-On Gear from Doc Johnson

Pair the Knuckle Up with a full strap-on harness or explore compatible harness attachments to expand your vac u lock collection.

More Harness OnlyBrowse the full harness only range.

All Strap OnsBroader category — every strap ons style.

Harness AttachmentsRelated couples pleasure pick — different feature set.

Plain-Box Shipping

3-Day Delivery

Veteran Owned

Body-Safe Materials

Discreet Toys is veteran-owned and operated. Every order ships in a plain brown box with a discreet billing descriptor — your privacy is the priority from checkout to doorstep. Questions about your order? Our returns & refund policy covers the details. Free shipping on orders $69 or more.

It’s only freaky the first time.

Last updated · May 20, 2026

📦 Discreet Shipping

Free Shipping
on Orders $69+

Or any product with a HOT label. Free Standard Shipping applies automatically at checkout, no code needed. Every order ships within 1 business day in a plain brown box.

Pick Your Speed at Checkout

Free on $69+

Standard Shipping

$7.95

FREE on orders $69+ or HOT items.
Arrives in 2–5 business days.

Priority Mail (USPS)

$17.95

$9.95 on orders $69+.
Arrives in 2–3 business days.

Priority Mail Express (USPS)

$49.95

$41.95 on orders $69+.
Arrives in 1–3 business days.

Delivery days count from the day your order ships. They're estimates, not guarantees. Orders of $200 or more may be held up to 3 business days for verification before they ship. Packages over 5 lb add a weight-based charge, shown at checkout before you pay. Read the full shipping policy

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Plain Brown Box

No logos and no product names on the box. The label never says Discreet.toys or what's inside.

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Discreet Billing

Your card statement shows DT WELLNESS STORE, never Discreet Toys or what you bought.

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Tracking by Email

We email your tracking number once your order ships.

How Your Order Arrives

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Order Placed

Pick your shipping speed at checkout

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Packed Discreetly

Plain brown box, discreet label

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🚚

Ships in 1 Business Day

Tracking emailed to you

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🏠

At Your Door

2–5 business days on Standard, sooner with Priority or Express

Veteran Owned

Orders +$69 or Hot - Free Shipping

Discreet Questions?

Text Us! 813-602-2480

Discreet Questions? Text Us! 813-602-2480

"It's Only Freaky the First Time!"