4" X 15/16" Non-Marking Monotech (Donut) Swivel Caster, Tread Lock Brake, Loads Up To 150 lb 4 in, Wheel Width 15/16 in, Wheel/Tread Material Rubber, Wheel Core Material Polypropylene, Non-Marking Yes, Number of Wheels 1, Caster Brake Type Side Pedal Brake, Tread Shape Donut.