Air Grinder,4-Inch Air Wet Stone Polisher 5500 Rpm with Rear Exhaust,Air-Powered Stone Polisher 1. Less weight 1.2 kg (about 2.8lbs),high power-to-weight ratio for reduced operator fatigue. 2.Air Consumption: 16cfm(0.45 m3/min ) 3.Air Pressure:90Psi(621Pa) Air Inlet1/4 Npt 4.Shaft Thread: 5/8"-11 5.Free Speed: 0 to 5500rpm