Originally Posted by
Dan Burkhart
Sturmey Archer anti rotation washers part number SU-HMW534 are made for vertical dropouts.
So that's what those things are for.
Oddly enough, both of my hubs had the anti-rotation washers for the narrower Raleigh dropout slots, and I had no idea that there were washers for modern dropouts, so I had shims in the dropouts of both of my bikes until I happened on a part number for the proper washers by accident.