I have a leaking shower at home and decided to try and fix it today. When I opened the tap I found a small metal valve with no rubber on it at all. Instead it had a metal ridge around the edge. The seat has a corresponding ring so I assume it's supposed to be this way. Both hot and cold were the same.
It's smaller than the standard valves I have in other taps around the house. It might be the smaller standard that you see in basin sometimes but I didn't have a small one to compare.
I've never seen anything like this before.
What's it called? If there is no rubber that is degrading, why is it leaking? Will it be easy to buy a replacement at the hardware store?