100 WATT BT15 HALOGEN SOFT WHITE 4000 HOUR ENERGY SAVING LIGHT BULB - Supra Life halogen bulbs  use a rigid quartz capsule for durability with a rugged CC-8 filament, while providing 15% energy savings compared to standard bulbs. Nickel plated bases prevent socket freezing and minimize heat. Rated at  up to 6,000 hours, Industrial Grade BT15 halogens will last and average of 12 months in commercial and retail applications, while providing up to 4 years of life in normal household applications.