Manifold valve isolates pump from the system when testing for leaks. Gas ballast valve helps prevent oil contamination caused by high moisture. Center oil fill ports is accessible from front as well as sides. Durable lightweight die cast aluminum housing. Oil drain valve positioned at bottom of oil reservoir assures maximum drainage This single stage vacuum pump has a 1/3 horsepower motor with a pump speed of 1725 RPM. Free air displacement is 2 CFM. Delrin vanes provide quieter, longer lasting performance. internal check valve stops oil blowout in case of accidental power loss.