Ryobi OP40401 40V 4.0Ah Lithium-Ion Battery Pack
This OP40401 lithium-ion battery works with Ryobi 40V cordless power tools such as RY40406, RY40540, RY40530, RY40620, RY40250, and more (sold separately). Charge it on compatible Ryobi 40V li-ion chargers including OP401 (sold separately).