Kockney Koi Yamitsu Algae Master UV O Ring
This Kockney Koi Yamitsu Algae Master UV O Ring goes over the outside of the quartz sleeve and should be replaced when adding a new quartz sleeve.
These seals become brittle with time and need to be replaced at least once a year to avoid water bypassing the seal and coming in to contact with the electric bulb. Genuine spare part