One of those collars is a separate piece, I've replaced those before when they've broken the bolt, the other though is part of the butterfly, that will be harder to source IF you end up ruining it. The bolts tighten down onto a flat section on the chromed rod it's mounted on, so that when the butterfly is pulled by the cables it turns the rod. I drilled mine out and helicoiled them afterwards, just be careful of marking the rod. Rods are available in stainless if you require one, I have a couple spare but I'm in the UK. I tend to replace those bolts with stainless ones so they don't rust and break in the future.
