Plain Linear Pillow Block Bearing PMN50C 50mm Open, Compensated IDOpen Plain Linear Bearing Pillow Block with a 50mm ISO Metric inner diameter and a compensated running clearance of 0. 0015" per side. A mountable standard aluminum housing encloses the bearing, which features a self lubricating, maintenance free liner made from FrelonGOLD for enhanced performance in harsh conditions such as extreme temperatures, dirt and vibration. Optional liners: corrosive chemical resistant FrelonJ & FDA compliant FrelonW Anodized