Ideal for general utility trucks, platform trucks, and dollies. Swivel casters have hardened double ball races and heat treated king bolt for long life. Wheels roll easily on cage type hardened and ground roller bearings. Features slotted bolt holes that help align screws to mounting surface. 4-1/2" x 4" plate size. 2-5/8 to 3 x 3 to 3-5/8 bolt spacing., Lot of 1