The Astro 320 ONYX Micro Sander is the smallest and most powerful sander in its class - boasting a 0.4 HP rating. Featuring the latest technology in ultra-compact machined internals, this sander is ideal for spot sanding focus areas. The Micro design makes it perfect for reaching smaller areas and tighter contours with less user fatigue. Full length with pad of 3.3"; Includes 2" (20301P) and 3" (20302) PU Velcro backing pads. Specifications: Pad Size: 2" (also works with 3") Spindle: 5/16"- 24 (Female) Free Speed: 19,000 RPM Air Consumption: 3.1CFM Air Inlet: 1/4" Motor: 0.4HP Pressure (bar): 90psi Exhaust: Side Weight: 1.1lbs Length: 3.3"