Xtr v brake bolt washers, necessary?

[ishaw]

I'm sure I've run these brakes without, but having just sold a set, it was missing one which I pillaged from another set to make sure the buyer got a complete set of brakes and all the fittings they came with.

If they are necessary, what do they actually do?

And, where can I get some from as I've a need for at least one now.

 

[Paul R]

They help hold the lower pivot cam on its cross section mount properly as in this pic i did when i seviced mine