domed washers on brake pads

[samsbike]

I have noticed that the older brake pads did not use domed washers and newer ones do - why is that?

Its also the same on some seatposts like thomson and VO, who used domed washers but others dont seem to.

[Brucey]

it is to allow the bolt to articulate slightly without seeing any bending stress in the case of the seat posts etc. (Some designs need it and others don't.)

On brake blocks it is to allow the toe to be set.

cheers