Exclusive VAC-U-LOCK System The Ultimate Strap-On Vac-U-Lock Ultra Harness 2 and Plug is the toy for men and women! It's simple to use even for first-timers. Start with the Ultimate Strap-On and Plug. Then you must add some of the deluxe Vac-U-Lock Powder to make sure your dong attachment stays locked tight. When you snap-on your choice of dong or realistic cock, you're ready for some serious action. You can last all night and into the next day! The harness has adjustable straps that makes wearing it extremely comfortable (up to a 44-inch waist).