The WristRattler is a creation from the minds of Dave DePew of Grinder Gym and Ryan J Pitts of StrongerGrip. The Wrist Rattler is a super comprehensive tool for wrist and grip. It offers a myriad of angles to be trained from, it gives you options to be used with Bands, Pulley machines and with free weights. You get the Base WristRattler unit 1.9" diameter, loading pin that threads in when you want to use weight plates and threads out when you want to hook the WristRattler up to bands or pulley machines. You can choose what loading pin you want, for olympic plates(big hole in center) or standard plates(small hole). Loading pins come with collar.