Model : 109 RM Lamp Type : 1 X 09 W CFL Accumulator : Ni-Mh Ni-Cd Rechargeable Battery Battery Backup : 4 Hrs Consists of single or more Fluorescent tubes which provides illumination on normal mains power supply and the same tubes continues to provides illumination during mains failure on self contained battery source. On resumption of mains supply the tubes switch back to the mains automatically and simultaneously recharge the battery to the required level. All maintained models provides uninterrupted illumination.