In the event of battery failure, this External Battery Pack can be used to access the Barska Biometric Safes by plugging it into the module on the safe. The battery pack will supply power to the module, allowing you to access the safe with your registered fingerprints to change the batteries. Compatible with Barska Safe Models: AX11224, AX11620, AX11650, AX11652, AX11898, AX11780, AX11556, AX12038, AX12408. Another quality product