Does anyone know what these are called or where I can buy them?
It is a plastic cover, around 8" in diameter (they probably come in a range of sizes), with a couple of dimples in them to allow them to be gripped to be screwed into or out of a base piece mounted in the wall, usually white/cream/magnolia in colour. Usually a valve or earth bond or similar behind them, normally found in newish properties of up to 10 years old.
It is a plastic cover, around 8" in diameter (they probably come in a range of sizes), with a couple of dimples in them to allow them to be gripped to be screwed into or out of a base piece mounted in the wall, usually white/cream/magnolia in colour. Usually a valve or earth bond or similar behind them, normally found in newish properties of up to 10 years old.