Double Roller Pillow Block Bearing DPB-48-OPN-TG for a 3" Shaft, Top Grease Lubrication PortDouble Roller Roller Pillow Block Bearing (DPB), with a top grease lubrication port, for a 3" Diameter Shaft, which has two sets of 3 opposing roller bearings while maintaining the standard size open bearing profile of a Single Roller Pillow Block (SPB); thus the term "Double." By contrast, a Twin Roller Pillow Block (TWN) also has two sets of 3 opposing roller bearings, but the TWN blocks are twice the size as if they were two SPBs fused together.