Rubber outdoor tiles that interlock are made for the home gym flooring market. The black recycled rubber tiles with 10% gray specks give the gym floor a high-end appearance. Rubber tiles that are 5/16 inch (8 mm) thick minimize vibrations from workout equipment like treadmills while protecting the flooring. https://modutile.com/product/interlocking-rubber-floor-tiles-23x23-8mm/