The Philips HF-M Blue 124 LH TL/TL5/PL-L is a square non-dimmable, high frequency ballast to run:1 x 28 T5. This ballast has flicker free start,Multi lamp ballast, Compact power IC and energy saving of more than 25% compared with electromagnetic gear. The Philips HF-M Blue range is suitable for installations with emergency back up.