The Scotty Slip Discs are easily placed over the lock system of your rod holder. This allows you to adjust the height of your rod holder without having to unscrew everything and then tighten everything again. Perfect for the rod holder when trolling. Thanks to the material used, the Scotty Slip Discs will show very little wear which prevents the rod holders for sliding. A fantastic product that will make the life of a boat fisherman a lot easier!