Pfeiffer Balzers Oil Fluid Lubricant Felt Reservoir for Turbomolecular High Vacuum Pumps TMH/U 261Y thur 521Y and TPH/U 180 thru 520. The lubricant reservoir should be replaced at least once a year or when replacing the bearing of the pump. Lubricant Reservoir and Porex Rods are included (if needed). See AVAILABLE DOWNLOADS PDF below for replacing Oil Fluid Lubricant Reservoir. Pfeiffer Part Number PM 063 266-AT.