Amazon.com: Synergy Digital Power Tool Battery, Compatible with Ryobi RP4530 Power Tool, (Li-ion, 4V, 2000mAh) Ultra High Capacity, Replacement for Ryobi AP4001 Battery : Tools & Home Improvement
AP4001 Battery - AP4001 Batteries - Spare Module Type Ryobi AP4001 Replacement Lithium Ion (Li-Ion) Power Tool Battery