Double Thruster - Tar IceSmooth shaft lays on top of yours, for double penetration or thrust using only double thruster or lift and use yours. sling base stays on even when not hard. Designed to morph onto the base of you with concave shaft, fits for double penetration to thick base. HunkyJunk original design clutch cock ball sling keeps penetrator Double Thruster lock in place. Sling base keeps it on for double penetration or slide in it like a strap on. Firm enough to use