Our fun Play Zone kit contains the nine most used Xact-Fit sizes for shaft rings, ball rings, and cock & ball rings. We know you will be surprised at how this sizing makes all the difference. The Xact-Fit ring is premium quality and incredibly strong. We made them not too stretchy, so the rings are effective, but easier to get on and off than a metal ring. Each ring is stamped with its size so no more guessing! Silicone , will last longer than normal C-rings.