30 INCH APPLIANCE FLUORESCENT LIGHT BULB - REPLACES F18T8/CW/K30 WITH INDUSTRIAL GRADE QUALITY - Bulborama Industrial Grade energy-efficient linear fluorescent lamps are built stronger to last longer than standard grade fluorescents. Unique Krypton/Argon gas mixtures reduce energy consumption, and heavy duty triple-wound cathode guards provide burning life of up to five years and 24,000 hours. Extended life phosphors allow Industrial Grade lamps to retain consistent lumen output levels and outlast standard fluorescents up to 5 times!