Atom Pulse Outdoor Quad Skating Wheels Great soft material for outdoor surfaces 65mm x 37mm size - Popular size for outdoor skating and enough to give you a great sturdy base. 78A hardness - great for outdoor pavement - the higher the "A" number, the harder the wheel, this is a good version for outdoor use Outdoor recreation, on streets or sidewalks 5 great colors, sold in 4 packs so you can mix and match!