I'm stumped with this unknown socket type. I've bought a manual valve + lockshield set. I expected the tails to use an ordinary radiator tail allen key, which I have.
But it's this shape instead. Does anyone know the name of this? Hopefully I'll embarrass myself with how common and well known this is, but I have no idea. It's circular with 2 curved sections coming inwards.
But it's this shape instead. Does anyone know the name of this? Hopefully I'll embarrass myself with how common and well known this is, but I have no idea. It's circular with 2 curved sections coming inwards.
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