This rubber Gasket Ring seals the water inlet of the Filter Housing
This is the top gasket, the inlet of the water, coming from the UV filter, see photo.
To be used in the blue Pall FSI® X100 Housing Series.
Sizes in mm:
d 56x44x3
Over the years this gasket can wear and can start leaking. It is replaceable by releasing the UV filter from it's position and gently opening the top gasket.