Metromax Polyurethane Stem Casters with 900 pounds capacity per cart.  Non marking polyurethane flat tread and polyethylene hub. Ball bearing swivel and axle. NSF listed.  Polyurethane tread is long wearing, resists abrasion, non-marking and shock absorbing.  Chrome plated horns, stems, axles, and brakes (optional) are appropriate for dry environments and for medium duty applications. One donut bumper included with each caster.