Sport-Thieme Spring Locking Clamps for Weight Bars – attach, change weight plates, continue training. The Sport-Thieme Spring Locking Clamps for weight bars are quick-release fasteners that allow you to quickly change and secure weight plates on the barbell. They require minimal time, enabling you to resume your workout swiftly. The clamps fit all weight bars with a diameter of 28 mm, 30 mm, or 50 mm. The versions for 28 mm and 30 mm also feature plastic handles. Product type: Spring closure • Bar diameter: 28 mm.