Produces pneumatic pressure and vacuum to check calibration of gauges, switches, transmitters, and recorders. The contoured cushioned handles provide extra comfort while preventing the pump from sliding. The over-sized check valve provides smooth operation throughout the output range while the dual O-rings on all pistons ensure zero leakage. Patented Mash proof vent valve comes standard on all MVP-600s (No Needle Valve) and a non-oil based lubricant is used on all moving parts.