Cushion rubber tires on high-impact polypropylene wheel centers suit Cush-N-Tuf™ Casters for fragile loads, or for service outdoors, over rough floors, dockboard lips and elevator sills. Unlike pneumatics, Ace-Tuf® tires won't deflate and can't be punctured. Industrial duty ball bearings are standard in all wheels. The casters–cold forged double ball race swivels and matching plate steel rigids– are bright zinc plated to complement the natural corrosion resistance of the Ace-Tuf® wheel. Check the attractive prices, too.