A UV lamp is a scheduled replacement, not a failure item. Its UV-C output falls steadily through life while the lamp continues to light normally, so a reactor with visibly working lamps can be well below its dosing duty. Replace on elapsed operating hours against the measured intensity trend, not on the lamp going out, and handle the new lamp by its ends only. This is the 4-pin HP lamp. Check the pin count and the HP designation on the existing lamp before ordering: this catalogue lists several SLR32143 variants and they are not interchangeable. Wedeco was founded in Herford, Germany in 1976 and is now a Xylem brand.