The Brand New Rome Tech ML1220 3V Rechargeable CMOS RTC BIOS Back Up Battery is a high-quality coin cell/button battery designed for consumer electronics. With a voltage of 3V and a battery size of 1220, this rechargeable battery offers reliable power backup for various devices. The Li-Al Alloy-Manganese Dioxide chemical composition ensures long-lasting performance and durability, making it an ideal choice for use in electronic devices that require a backup power source.