This is the replacement Lynx back up battery for the Honeywell Lynx panels. It is meant to be a 24 hour back up battery for Lynx panels that have a cellular radio. This battery has a three pin connector.
Battery Specs: 7.2VDC Output and 3700mAh.
The smaller batteries have a connector for two pins (two small holes) and this larger battery has a pin connector for 3 pins (3 small holes).
It is found inside of your Lynx Keypad and you just need to use a flat head screw driver to push the tabs to open the front of the keypad and see the back up battery. Just unplug the old one and plug in the new one and you are done.
If you are not sure if you have a Lynx keypad look here and see some of the different versions. They all use the same back up battery.
Look here if you are looking for instructions on how to replace the battery.