Offering flicker free start 1-100% dimming and constant light output this Single HE High Frequency Ballast from Huco Electronics is a trusted and reliable option for 21 Watt T5 Fluorescent lamps. With a 50000 hour service life and a 60% reduction in energy consumption compared to conventional ballasts this slim lightweight unit is a popular choice in offices supermarkets public buildings and educational establishments. Additional features include silent buzz free operation automatic shutdown at end of life and smooth warm lamp start.