You are purchasing one Piece of Supreme Pondmaster 40 Watt UV Replacement Bulb for Ultraviolet Clarifier - 12974 10,000 Hour Long Life Lamp 6 Month Warranty Includes Free Gloves for Handling 100% Compatible with the Danner Pondmaster 12974 Guaranteed to meet or Exceed Manufacturers Specifications UV Hot Cathode Germicidal UV Bulbs (UV-C), are low-pressure mercury arc lamps that are the most effective tool for eliminating microorganisms such as virus, bacteria, mold and yeast in the air and impurities in water. Produces UV-C (253.7 nm wavelength) radiation (harmful to eyes and skin). Specifications: PART NUMBER: 12974 FAMILY: Germicidal UVC Lamps WATTAGE: 40W AVERAGE LIFE: 10,000 Hours BASE TYPE: 4 Pin PIN PATTERN: Square Box BULB SHAPE: T-5 (T5) T5F LENGTH: 19.68 in. (500mm) FAMILY: Germicidal UVC Lamps DIAMETER: 0.61 in (15.5mm) ENDS: Single End BULB FINISH: Clear BURNING POSITION: Universal Burn OUTPUT: UV-C SPECTRAL PEAK: 253.7nm Buy Wholesale from the Importer. We stand behind our products and Guarantee Same day Shipment and 100% Buyer Satisfaction.