Stem cap required

I need a new stem cap, will any cap fit any stem? And where would a get a grey or silver one?

This is a serious question, despite appearances.

Would that be an African or a European stem cap?

ok the black magic seems to be working..you are nearly completey senile !

Now lets not let this descend into farce, this is important.

flat cap for imperial stems, baseball cap for american standard...