Dynabrade 18066 2-3/4-Inch by 16-Inch Long Board Reciprocating Sander This dual piston, in-line action, non-vacuum board sander provides consistent finishes over a large area due to the 16-Inch long backing pad Tool features smooth-running in-line sanding action at 2,500 strokes per minute with a 1-Inch long sanding stroke For use with PSA (adhesive-backed) coated sheets 2-3/4-Inch x 16-Inch or 2-3/4-Inch x 17-1/2-Inch sheets for smooth-face rubber pads with clips