The lite plan hrnt542122 module is a 3hr emergency lighting module specifically designed for use with 21w amp 22w t5 circular fluorescent lamps4 pole change over relay plus additional 5th pole for hf ballast isolation this lite plan conversion kit has the following benefits specific t5 lamp calibration to maximise blf 4 pole changeover relay additional 5th pole relay deep discharge protection low profile enclosure constant current charger and high temperature nicd cells