Pneumatic Straight-Line Sander's dual-piston design has extra power for demanding sanding jobs Eastwood-engineered Straight-Line Air Sander uses those dual pistons to generate the extra power needed to avoid stalling when the sanding gets tougher. That makes it ideal for smoothing body filler or shaping larger surfaces. 2,100 strokes per minute Power-generating dual-piston design Variable speed lets you match speed to job 2-3/4" x 15-1/2" sanding pad Uses just 5 cfm at 90 psi, so runs on DIY compressors