SU420 battery for APC Smart UPS 420 SU420 - Compatible Replacement by UPSBatteryCenter 100% Guaranteed - Compatible Replacement Battery for the APC Smart-UPS 420VA Guaranteed compatibility with: SU420 In-Stock and Ready for Immediate Shipment - 1 Year Warranty included! Direct replacement, Fully charged, and ready for use. Manufactured & sold exclusively by UPSBatteryCenter