Pillow Blocks are referred to the housings that have a bearing fitted into them. Pillow blocks are usually mounted in cleaner environments and are usually meant for lesser loads. SERIES INFORMATION:Bearing Inserts Split 4-hole 2-hole Mast Guide Bearings MQ305-2RS-1 InchMetric Ref: VCP PB RAK UCP SFT ABX is an authorized distributor for many major bearing manufacturers and an indirect distributor for all major brands of bearings.