48 inch T8, case of 25 tubes 13 watts, 1900 lumens, 3500K Type A & Type B LED Tube-Type A mode allows for simple initial installation (plug & play). To use Type A+B lamps as Type B, the fixture must be re-wired. Double-Ended Type B mode works on shunted or unshunted sockets Type A+B Tubes can run off a ballast initially, and can run off mains voltage should the ballast fail, or if it is found to be incompatible (requires re-wiring to utilize as Type B)