This Philips HF-R TD 255 PL-L dimmable ballast runs 2 x 55w PL-L. This ballast\'s lamp power can be regulated from 1% to 100%, digital control input according to the industry-standard DALI (Digital Addressable Lighting Interface) combined with the Touch and Dim pushbutton protocol. 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.