Material: The barbell spinlock collars are made of high quality iron material, are chrome-plated, durable and corrosion-resistant and can be used for a long time. Size: The non-slip collar of the barbell is suitable for 25 mm standard barbells or dumbbells. Please check the size before purchasing. Anti-slip design: The dumbbell screw clamp is equipped with an anti-slip rubber ring and ensures that it can be safely and securely attached to the dumbbell or barbell bar. Package Contents: 4 PCS x Dumbbell Spinlock Collars. Application: Perfect for use with bumper plates and for lifting platforms. Also a practical and perfect gift for fitness lovers. Product description Features: - Made of high quality material with anti-corrosion coating for permanent use. -The barbell nuts are easy and quick to move your weight plates around. -Can keep the panels safe and secure even while lifting. The use of the anti-slip spin lock is a guarantee of fitness safety. Specification: Material: iron with chromed material Size: 1 inch / 25 mm Color: silver Package includes: 4 PCS x Dumbbell Spinlock Collars Please Note: Due to manual measurement, there may be an error of 0-2mm. The colors displayed in the picture may not completely match the actual object due to the shooting method and display device. Please make sure you don't mind before you buy, thanks!