Robinair's CoolTech 2-stage rotary vane design vacuum pump features the power and capacity needed for a wide range of service applications as well as robust construction for a long service life Powerful 1/3 HP, 115V/220-250V - 60/50Hz thermally protected motor, 94 liters per minute free air displacement, and factory rated to 20 microns for a fast, thorough evacuation Offset rotary vanes build powerful compression within the pumping chamber - reducing pressure and vaporizing moisture; durable molded polycarbonate base improves pump balance and minimizes vibration Iso-Valve isolates pump from system with just a quarter turn; Gas Ballast design mixes moisture laden air passing through pump with relatively dry air so compression doesn't cause condensation 1/4 inch male flare and 1/2 inch ACME inlet fittings, easy to read sight glass, easy access oil fill port, and angled oil drain valve for faster, more complete draining of the reservoir