Accessory, Caster, Plate Swivel - Pneumatic, 7"W x 7"D x 7.5"H, Rubber, 6"dia. x 2"W Heavy-Duty Swivel Plate Caster w/ Zerk Grease Fitting, 5lbs. (ITEM WEIGHT ONLY), overall height (w/ mounting plate) 7-1/2"H, pneumatic feature allows tire pressure to be adjusted by use of a tire pump