The core of our polyurethane training plates is constructed from robust iron. The outer layer is coated with polyurethane, ensuring that the barbells wonâÂÂt damage the floor if dropped. This protective coating is both waterproof and wear-resistant, making it easy to maintain. The barbell features three hand grip holes, allowing for easy handling when the plates are on the ground, enhancing their convenience. Additionally, the product has successfully passed a rigorous drop test, enduring 20,000 drops from a standard height without any damage.SPECIFICATIONS Color Black + blue Material polyurethane + cast iron Weight range 1.25-25kg Aperture 51mm Bell diameter 179.5/224/280/320/360/419/448mm Bell thickness 21.5/29.5/29/40/45/45/46mm