The Robinair 15150 is a VacuMaster 2-Stage Vacuum Pump. It has heavy-duty motor and high torque design for easy startup and efficient operation. The oil fill port makes adding oil simple since the port is accessible from the front or either side. It has a sight glass on the front of the pump which shows user when enough oil has been added. The durable polycarbonate mobile base improves pump balance and minimizes vibration during operation. Die-Cast aluminum housing makes the pumps lightweight but durable. Its two-stage design cleans the system more thoroughly than a single-stage pump; the second stage starts pumping at a lower pressure so user can pull a deeper, ultimate vacuum.