Peugeot 207 rear disc brakes, top calliper mounting bolt has what looks like a valve attached to it, there are no wires or pipes going to it, anyone got any ideas.
100% certain it is not the bleed nipple. The bleed nipple is on the calliper itself, The part i am talking about is on the top calliper mounting , normally just a 13 mm bolt, but this has some sort of valve,?