The Knuckle Up is a unique take on harnesses for Doc’s Vac-U-Lock System. The piece resembles a pair of brass knuckles in design, but above the knuckles is a plug that securely holds any of the attachments in the Vac-U-Lock line of products. The Knuckle Up allows for a better grip and greater leverage every time.

Website: DocJohnson.com
Retailing: The Knuckle Up can be used with any Vac-U-Lock individual products or complete set.
Colors: Black
Materials: ABS
MSRP: $