GTU Furniture Bed Frame Replacement Caster Wheels/Rug Rollers with Socket Inserts Cups (4) This rug roller is designed for use with bed frame This listing is for FOUR(4) wheels, and FOUR plastic inserts that get inserted between the wheel and the bed frame It has a 4.2" x 2.2" Silvery Zinc Caster, with a 0.5" x 1.8" Grip Neck socket stem These durable bed casters have a load capacity up to 110 pounds each Come in brown polypropylene wheels, with a Silvery zinc finish