FAIRBANKS Casters offer larger, hot forged, 1-piece, king bolt construction and lower ball raceway. Heat treated upper and lower ball raceways. Hardened roller bearings and ground bushings. Grease seal ring on upper ball raceway keeps dirt out while holding larger reservoir of grease. No-weld construction on caster horn assures greater strength. Slotted bolt holes for 2-5/8x3-5/8" or 3x3" centers.Wheel type codes are:SS—semi-steelMR—mold-on rubber,PO—polyolefinPU—polyurethanePH—phenolicMR-HC—mold-on rubber high capacityTPR—thermo-plastic rubberBCI—blue polyurethane on cast aluminum hub