Plummer Blocks are bearing boxes for self-aligning roller or ball bearings. Depending on the application, the plummer block has a built in felt seal, rubber seal or labyrinth seal as the sealing device. Each type is lubricated using grease or oil. The standard bearing box body is cast iron, but (depending on the application) may also be made of spheroidal graphite cast iron (ductile cast iron) or cast steel. (Ref. catalog "Plummer Blocks" CAT. No. 2500E etc.)