Howard 1or 2 Lamp F54T5HO Multi.Volt, Programmed Rapid Start electronic ballasts. Series circuit configuration. 120-277 Multi Volt feature. Ballast Case is 16.7" OAL x 1.18" Wide x 1.0" High. Ballast shall be UL certified with a 5 year manufacturers warranty. Operates 1 or 2 F54T5 High Output Fluorescent lamps.