Wow... I don't know how all of you guys do it. If I do anything more than just wear my binder under whatever clothes I would ordinarily wear, I feel like I'm suffocating from the heat. As it is, in the summer, the binder alone is far too much.
I use the Underworks cotton concealer compression muscle tees--- I've tried the double front, and I know I'd need an undershirt to go under one of those, but the spandex on the cotton concealers is soft enough to go without an undershirt. Just have to watch out for chest hair catching in the spandex!