The Powerex MHR9V Rechargeable NiMH Battery (9.6V, 230mAh) is a nickel-metal hydride battery compatible with Powerex"s MH-C1090F 10-Bank Charger or MH-C490F Stealth Charger. It has a voltage of 9.6V and a capacity of 230mAh. It has the ability to outperform a standard 9V battery due to its slightly higher voltage. The MHR9V is free of memory effect, a condition which can cause batteries to hold less charge over time, meaning it will retain its full charge without conditioning. The battery is rechargeable up to 1000 times. The purchase of an NiMH battery like this one saves you money, since you won"t need to buy endless supplies of non-rechargeable alkaline batteries.