High Capacity: 650mAh 6F22 9V lithium-ion rechargeable battery last longer for one charge , great batteries for backup application. Please charge before use. No Memory Effect: As 9V lithium batteries dont have any memory effect, these 9v batteries can be charged at anytime, and they can be charged up to 1500 times. Low Self Discharge: They will hold charge for 1 year and can maintain 75% of capacity after three years of storage. Applications: These batteries are ideal for fire alarms, home security devices, and professional audio and medical devices. You Can Get: 4 Pack 650mAh 9v rechargeable batteries.