Premium Materials: These barbell ring attachments are made of solid steel with rubber grips. Allows for rapid weight changes. A must-have accessory for garage weight rooms and fitness studios, from weights to workouts. Fits 25mm Barbells: Weight clamps fit any 2.5cm bar or barbell. (Note: This product cannot be used with threaded rods, only with polished rods.) Prevent the board from slipping: This dumbbell spring prevents the weight of the board from slipping off the rod. Superior spring tension and adjustment keep your skateboard still and safe during daily workouts and basic lifts. Removable Plastic Handles: Each collar has two removable plastic handles for extra grip even during sweaty workouts. EASY TO USE: This dumbbell spring is easy to use and slides down the bar with a quick push. Stay safe while exercising.