Ball-cock / Float Valve Diaphragm Washer

Diaphragm washer for brass part 2 or plastic part 3 fill / float valve / ball-cock.

Replacing this washer can often fix problems with slow filling toilet cisterns and ball-cock valves that won't shut off.

One side is different from the other, make a note of how the old washer was fitted and re-fit the new one the same way round.