"Fairbanks 4-caster set includes two swivel and two rigid casters that are ideal for trucks and dollies, cargo containers, freight trucks, service carts and more. A revolutionary long life one-piece fork/horn design distributes the load more evenly, plus a one-piece combination lower ball race and kingpin improves rigidity and provides easier swiveling. Mounted on 4 in. x 4 1/2 in. top plate with bolt hole spacing of 2 5/8 - 3 in. to 3 in. - 3 5/8 in. Wheel Diameter in. 6, Finish Type Gray powder coat, Bolt Hole Spacing 2 5/8-3 in. to 3 in.-3 5/8 in., Caster Type 2 Swivel, 2 Rigid, Casters qty. 4, Material Type Polyolefin, Wheel Type Low maintenance plain bore, Capacity lbs. 2,600/set 650/ea. Total load capacity for 4 casters is 2,600 lbs. 650 lbs. ea. Cold-forged 3/4 in. kingpin provides superior strength and stability Low maintenance plain bore 6 in. wheels to handle medium duty loads Nylon grease seal ring on the upper ball raceway keeps dirt out and retains a large grease reservoir Gray powder-coated finish prevents rust One-piece construction - fewer parts means less chance for failure"