A Pillow Block Bearing is a mounted anti-friction bearing that is contained within a solid cast iron, ductile iron or cast steel housing unit. Also referred to as a housed bearing unit, meaning they are self-contained, greased, sealed and ready for installation on the equipment. Pillow Block bearings are typically bolted to a surface, so that the attached shaft runs parallel with the surface. There are two types of housings used for pillow block bearings, solid and split housings. http://www.ghbearings.com/pillow-block-bearings/