FC30/CW CIRCLINE FLUORESCENT BULB - 30 WATTS - 4100K COOL WHITE - T9 SHAPE - 10 INCH DIAMETER 4 PIN BULB - Bulborama Supra Life energy-efficient linear fluorescent lamps feature a unique Krypton/Argon gas mixture to reduce energy consumption. Heavy duty triple-wound cathode guards provide burning life of up to five years and 44,000 hours. Extended life phosphors reduce color shifting, provide consistent lumen output levels, and allow Supra Life fluorescents to outlast standard lamps up to 5 times!