This is a Philips Sterilamp® brand germicidal fluorescent bulb, ordering code 135020. This bulb has a 9000 color temperature, 8000 hours rated life and GX23 base. This bulb produces UVC radiation and is used to kill microscopic organisms in water purification and air disinfection systems.
You need to use caution when using this bulb as it can be very harmful to eyes and skin. DO NOT expose eyes or unprotected skin to these lamps, serious injury and blindness could result.