Philips 381863 5-watt PL-S TUV Germicidal with  2-Pin Base Light Bulb For residential drinking water, water and air treatment units, stand-alone purifiers and deactivation of bacteria, viruses and other micro-organisms Short-wave UV radiation with a peak at 253.7 nm (UVC) for disinfection purposes Lamp glass filters out the 185 nm ozone-forming radiation Warning sign on lamp indicates that the lamp radiates UVC G23, 2-pin Base - 2-Pin PL-S lamp base contains a special starter for almost instant starting on electromagnetic drivers