The Pura 89521 is the correct replacement UV sensor for the following filter systems:
The PURA 89521 Replacement UV Sensor - UVSS-15M fits the Pura UVSS-15M ultraviolet water filtration system. This Pura sensor detects the discrete 254nm wavelengths of the UV lamp, and relays this information to the controller. The UVSS-15M sensor indicates when the UV bulb loses effectiveness.
PURA 89521 Replacement UV Sensor - UVSS-15M specifications: