5" x 1-1/4" Polymadic Wheel Square Swivel Stem Caster - 350 lbs. Capacity5" x 1 1 4" Polymadic Wheel Square Swivel Stem Caster The polymadic wheel provides plenty of durability with a firm tread. The polyurethane tread protects surfaces, and the annular bearings roll very smoothly. These wheels work well for most hard floor applications due to the high performance UV resistant materials used. Tread: High Performance UV Resistant Polyurethane, Non Marking, Mechanically Locked To Core Core: Polyolefin Bearing: Ball Bearing