Plain Linear Pillow Block Bearing PM30C 30mm Closed, Compensated IDClosed Plain Linear Bearing Pillow Block with a 30mm ISO Metric inner diameter and a compensated running clearance of 0. 0015" per side. A mountable standard sized aluminum housing encloses the bearing, which features a self lubricating FrelonGOLD liner for maintenance free operation in harsh conditions like extreme temperatures, dirt and vibration. Optional liners: corrosive chemical resistant FrelonJ & FDA compliant FrelonW Anodized Aluminum Bearing