iSpring UVB11 Replacement Lamp / Light Bulb for UV Disinfection Water Filters, 11 watts, 1-GPM; 5/8" x 8 1/4"; Last 8,000 hours Kills 99% of bacteria, virus, and protozoan cysts. Perfect solution to purifying well water and other problem water sources containing excessive microorganisms like water from lakes and streams. 11W Germicidal UV lamp, Philip Brand, Fits iSpring UVF11/UVF11A Approximate dimensions: Dia 5/8" x 8 1/4" L (not including the pins) Flow rate: 1GPM; Last 8,000 hours