BR 18/11 WALK BEHIND AUTO SCRUBBER - Cylindrical 18 brush. 1300 RPM with 50 lbs of brush pressure. Scrubber has an 18 cleaning path. - 17,969 square ft per hour cleaning rate. Sound level of only 66dB. - Built-in on-board charger for quick and easy charging. - This machine is easy to clean and has vacuum motor protection.