STIHL RMA 510 V 21 in. 36 V Battery Self-Propelled Lawn Mower Kit (Battery & Charger)Just the squeeze of a lever engages the RMA 510 V battery powered lawn mowers efficiency driven performance, helping reduce user fatigue commonly caused by traditional push mowers. A 21 inch deck with a 20 inch cutting width makes the RMA 510 V highly maneuverable and able to quickly cover small to medium size yards. The mowers self propel function features a variable speed setting control, allowing the user to choose a mowing speed between 0. 6 mph