Our Weightlifting Olympic Bumper Plates are constructed to fit a 35mm barbell sleeve and conform with the International Weightlifting Federation norms. Our 5kg plates have a standard diameter of 450 mm. They are constructed using a steel core covered with the highest quality neoprene rubber to provide the optimal bounce when you drop the weight. The 5kg are coloured according to IWF specs as well. These plates are available individually as well as part of our Challenge Barbell Olympic Lifting Set.