I was having a problem with my barbell plates not sitting on the loading pin in a flat manner. They would slide to one side of the loading pin and sit askew, so the plates would swing considerably anytime you did facepull, tricep pushdown, and lat pulldown exercises.
I designed this to help alleviate the swaying of the plates so they don't bump into you, the floor, or anything else!
Designed for olympic-sized plates with a hole diameter of 2 in (5.1 cm). The loading pin I use has a diameter of 0.8 in (20 cm). You want a clearance of 0.5mm between the parts you're mating together (loading pin → ID of stabilizer, OD of stabilizer → barbell plate hole) for a good fit.