This small battery is commonly used in many laptop computers.

CMOS & Clock Backup batteries maintain the time and date of the device when it is turned off, thus insuring their accuracy when the system is once again restarted. The battery saves the computers BIOS set-up configuration, so the system can be efficiently rebooted once it is switched on again. For example, the computer knows what type of hard drive it is booting from.
These batteries are also known as CMOS batteries, Real Time Clock (RTC) batteries, PRAM batteries or simply internal batteries.

20mm x 3.2mm

3 Volt

IMPORTANT!!!!  Please check the end connector as they do come in two different size and shapes. Please make sure it is identical to the connector pictured.