The Delta Fitness Magnetic Barbell Collars features are made of high quality aluminum that is made to last. No more will you be searching high and low for your collars after unloading your last lift. You can now quickly slap them right to The Wacker Wall Rack uprights or any other steel surface and the collars will be right there waiting for you. Sold as a pair and guaranteed to hold firm, yet slide easily. Designed with a two click collar design, you will feel the collar tighten on the first clip and completely secure on the second. In reverse when removing the collar, you will also feel the immediate space created on the second click. These clamps fit 2" barbells.