Greenworks 40V 4.0Ah 21-in. BL (Smart Pace) Self Propelled Mower with (2) USB batteries and (1) charger included. The Greenworks 40V Lithium-Ion platform powers over 40 outdoor products, including lawn mowers, leaf blowers, string trimmers, chainsaws, hedge trimmers and much more! Our 40V lithium-ion batteries provides the power you need, and deliver fade-free power with no memory loss after charging