VAC-U-LOCKWe consider our patented Vacu-Lock System the have all, be all of harness systems to date. Countless colors, shapes and sizes to chose from. All Vacu-Lock pieces are interchangeable so you can take your dong from harness to suction cup to double dong to Ez Rider Rocker with a simple plug in. The Vacu-lock system has a proven track record of quality and dependability. You'll have more fun and more sex with your Vac-U-Lock system!