Lables on Fluorescent lamps can be confusing. Lets use an example: F40T12CWSSECO
F = Fluorescent
40 = Wattage
T = Tubular
12 = Size; 12/8" or 1½" Diameter
CW = Color: Cool White
SS = Super Saver in this case 34 watts
ECO = Ecologic or Environmentally Friendly (low mercury)