This Philips HF-R TD 224 TL5 PL-L dimmable ballast runs between 2 x 24w T5 fluorescent tubes and 2 x 24w PL-L. This ballast s lamp power can be regulated from 1% to 100%, automatic stop start, automatic restart after lamp replacement, up to 75% reduction in energy consumption and quick programme flicker free start.The Philips HD-f ballasts are commonly used in offices. These units are for use with installations with emergency back up.