Vac-U-Lock Dual Density Starter Set by Doc Johnson

Three dual-density strap-on attachments that warm to body temperature, combining soft outer layers with firm cores for realistic penetration that bends and flexes like actual flesh. Perfect for couples exploring strap-on play or partners seeking authentic sensations over rigid alternatives.

What it does

Each attachment combines a soft outer layer with a firm inner core, creating sensations that shift as your body heat warms the ULTRASKYN material during use. Rather than staying cold and rigid, the exterior softens and flexes naturally against sensitive tissues, while the core maintains enough structure to deliver satisfying pressure. This dual-density design means penetration adapts to internal contours and responds to movement, bending with your partner's body instead of forcing them to adjust to an unyielding shape.

Realistic texture and warmth trigger deeper psychological arousal because the sensations genuinely mirror penis contact rather than artificial silicone. Physical friction builds naturally without overwhelming sensitivity, and as arousal intensifies, responses deepen. Orgasms tend to arrive with more consuming intensity when penetration feels lifelike—body-shaking releases that leave you trembling from what your nervous system registers as authentic contact. Browse Strap On Me for the complete range of harness styles and attachments.

Specifications

• Attachment one: 7-inch thin dong with 2-inch diameter
• Attachment two: 6-inch spiral dong with textured ridges and 1.5-inch width
• Attachment three: 5.5-inch textured cock with realistic head and 4.5 inches insertable depth
• Material: ULTRASKYN dual density with body-safe construction
• Harness: Adjustable straps with removable O-rings
• Attachment system: Vac-U-Lock click-in mechanism
• Included: Suction cup base

Fit and sizing

Three different lengths let you progress gradually as comfort develops—start with the manageable 5.5-inch textured option and work toward the 7-inch thin dong as your body adapts. Size preference is personal; choose based on what feels right for your partner's comfort, not on ego or bravado. The harness adjusts around hips and thighs to sit securely without shifting during use. Cockringshop specialise in products for men and couples, and our team can help you find the right fit if you're unsure. Water-based lubricant applied generously to both attachment and partner ensures smooth insertion regardless of which size you select.

How to use it

Select your preferred attachment and press it firmly into the harness until it clicks into place—the Vac-U-Lock system locks securely and prevents slipping. Adjust the straps around your hips and thighs so the harness sits snugly without bunching or moving. Apply water-based lubricant generously to both the attachment and your partner's opening before starting, which ensures smooth initial contact and reduces friction-related discomfort.

Begin with gentle thrusting motions that allow the dual-density material to warm and soften against your partner's internal walls. Watch their breathing deepen as realistic sensations trigger genuine responses, then increase tempo when their hips start moving to meet your thrusts. After use, clean the attachment with warm water and mild soap, then dry thoroughly before storing. The harness can be wiped clean and air-dried between sessions.

Feature breakdown

Who it suits

Couples exploring strap-on play for the first time will appreciate having three different sizes to choose from as comfort develops. Partners who crave authentic penetration sensations rather than obviously artificial sex toys benefit most from the realistic texture, warmth, and flexible construction. Anyone with specific size preferences can start small and progress at their own pace, or stick with whichever attachment feels best. The harness provides secure positioning that lets the wearer focus on rhythm and connection rather than worrying about slipping.

Skip this set if either partner prefers clearly non-realistic sex toy aesthetics or rigid materials. Those seeking vibration or other motorised features won't find them here—this set focuses entirely on lifelike texture and responsive movement. If your interest lies in pure sensation without realism, other strap-on styles may suit you better.

How it compares

Rigid strap-on attachments stay hard and unyielding throughout use, which can feel less lifelike and requires partners to accommodate the sex toy's shape rather than the sex toy adapting to their body. Dual-density models like this one flex and warm to body temperature, creating sensations that more closely mirror authentic penis contact. Flexible materials bend with internal movement and soften during use, while rigid alternatives maintain constant firmness. Pornhub Sextoys includes other styles and materials if you prefer different firmness or aesthetic. Your choice depends on whether you prioritise realism and responsiveness or consistent rigidity.

What you can use it with

Pair this strap-on set with items from Couples Intimacy Kits, which complement penetrative play by adding extra sensation or control during partnered sessions. Cock rings worn by the receiving partner can intensify arousal and orgasm, while positioning aids help both partners find comfortable angles during longer sessions. Pairing penetration with other forms of stimulation creates layered sensation that deepens arousal and can lead to more intense climaxes.

More from Doc Johnson

Doc Johnson specialises in realistic ULTRASKYN adult toys with patented dual-density technology across multiple product lines. Doc Johnson offers other strap-on attachments, rings, and body-safe sex toys designed for couples and solo use. Browse the full brand range to find complementary products that suit your preferences.

Read more before you buy

New to strap-on play or want to understand technique, positioning, and safety better? Know About Strap Ons covers the essentials on the Adultsmart blog.

Why buy the Vac-U-Lock Dual Density Starter Set by Doc Johnson

Want firmer, longer-lasting results without the guesswork? Order the Vac-U-Lock Dual Density Starter Set by Doc Johnson from The Cock Ring Store—genuine, function-tested, and quality-checked for safety and performance. Cockringshop ships discreetly in unmarked packaging so your purchase arrives private and secure. The specialist store for rings, cages, and male enhancement — discreetly delivered. The Cock Ring Store ships discreetly Australia-wide.