HAK/1 Hush‑ActiV Grade C Domestic Fire Alarm Kit, 24V PSU, 72h BatteryC Tec HAK 1 HUSH ACTIV BS 5839 6 Grade C Domestic Fire Alarm Kit Conventional stand alone Grade C domestic fire detection system. Complies with BS 5839 6 (2019) standards. Ideal for use in individual flats and apartments. Includes a Hush ActiV controller with a 72 hour rechargeable battery. Attractive design with EN54 certified devices. Monitored for head removal and circuit faults. In excess of 10 years battery life.