Ryobi P197 Battery ONE + (PLUS) Compatible Replaces P108 Rechargeable Lithium Ion 18 v Volt 4.0 Ah / 72 Wh UL Listed Faster Recharge Single Battery with Fuel Gage - Amazon.com
Amazon.com : Ryobi AP4001 Genuine OEM Tek4e 4 Volt Compact Lithium Ion Rechargeable Battery Pack (Charger Not Included, Battery Only) : Cordless Tool Battery Packs : Tools & Home Improvement