1/4" Dr. Mini Air Die Grinder Front exhaust keeps grinding surface clean for visibility . Built-in air inlet allows for greater access in restricted areas . Safety lever throttle for positive speed control . Built-in speed regulator . Ball bearing construction for long tool life . Free Speed (RPM) @ 90PSI: 25,000 . Collet Size (In.): 1/4 . Air Inlet (NPT): 1/4 . Min. Hose Size (I.D.): 3/8 . Recommended Air Pressure (PSI): 90 . Average Air Consumption (CFM): 4 . Sound Level (dBA): 94.5 . Length (In.): 4.92 SX231B Yes - NICKEL (METALLIC)