RE: What is the rheostat housing on the HHA sights and how do I use it?
It isn't plastic. It is a machined aluminum ring that is held in place by three silicon like bumps on the main housing that provide enough friction so that the ring does not fall off but allows you to slide it back and forth easily.
Trust me, HHA takes no short cuts inthe manufacturing of their sights. There isn't any plastic on that sight any where.