Diaphram washer for Armitage hush flow inlet valves
Old Style For Screw Type Caps- Has a flat base
New Style For Twist-Lock Caps- Has a visible 'rim' on the base
Your old washer once removed could have visible ribs imprinted into the surface of the rubber. This is perfectly normal as the washer forms to the inside shape of the inlet valve body once compressed in and used.
