1. Product Overview NA12581SW/K38985 is imperial standard single row tapered roller bearing. NA12581SW : Inner cone assembly; SW suffix means chamfer design on cone front face for lubrication passage K38985 : Matching single outer cup Separable cone & cup construction enables independent installation, disassembly and inspection. It can withstand combined heavy radial load and unidirectional axial thrust. Normally installed in opposed paired layout to support bidirectional