This Philips HF-R 418 TL-D dimmable ballast runs a 4 x 18w T8 fluorescent tubes. 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.