Amazon.com: 40V 6000mAh Replacement for Ryobi 40v Battery, Replacement for 6.0Ah 40v Ryobi Battery OP4015 OP4026 OP40201 OP40261 OP4030 OP4040 OP40401 OP4050 OP40501 OP40601 Fit for All Ryobi 40V HP Series Tools :
RYOBI One Lithium Battery Power Tool Packs 18v 1.5Ah 28Wh Li-Ion Cell Harvesting - The Lithium Guys