ProsourceFit Bumper Plates are built with the highest quality for use in cross-training or commercial gyms but are also perfect for garage gyms and home use. These plates offer low bounce with a durometer of 88 (+/-5), so they won t fly around the floor when you drop them. The solid rubber design can withstand repeated drops and won't damage your floors like other plates. The narrow width of each plate allows you to fit more weight on your barbell. (Durometer measurements indicate the density of the rubber and how much a plate bounces when dropped, with 100 being hard with no bounce and 65 being softer with a lot of bounce.) The solid rubber bumper plates have a diameter of 450mm and the width varies from 30-60mm depending on weight. Solid rubber bumper plates have stainless steel inserts and fit on 2-inch barbell sleeves.