RadioShack 2.4V/800mAh Ni-Cd Battery for VTech It fits VTech models CS6128-31, CS6128-42, CS6129-2, CS6129-3, CS6129-31, CS6129-32, CS6129-4, CS6129-41, CS6129-52, CS6129-54 and more. Use this battery as a replacement for VTech BT175242 and BT275242 batteries in your VTech phone.