I got this "binder" recently. I like it better than any one I've had so far (I'd estimate that I've gone through about eight from various brands).
Pros:
-Very breathable, can exercise in it without feeling like death
-Not terrible in hot weather
-Doesn't show under a lot of shirts, though if you have a shirt with a wide neck it'll show, but does look like an undershirt as opposed to a bra since the neck is high.
-Helps with hiding hip fat
-Feels natural. I forget I'm wearing this sometimes. Probably would be fine sleeping in it as well, though it's good practice to take breaks.
Cons:
-If you have a bigger chest this isn't gonna do the best of jobs binding since it's got less compression than a typical binder. It's still not the worst option in that case, but you won't look completely flat. It's worked well for me flatness wise.
-I wouldn't wear this by itself because it doesn't fit like a regular shirt. Definitely looks an undergarment.
-It smells like a McDonald's playground right out of the package. I recommend you add baking soda into the wash to get the smell out faster.
-I suspect this will stretch out the longer I use it. The solution is to dry it on low as opposed to air dry it. It's got cotton in it so it'll shrink.
I recommend you only get it in black or white if your concern is passing. A lot of cis men will wear undershirts (typically in white, sometimes black, but never in nude).
If you're in-between measurements, order a size up. I made the mistake of getting a size down and I wasn't even able to get it over my head. Had to exchange it which took a while.
If you're interested in a binder with flatter coverage I will post a review of the underworks ultimate binder if requested. Underworks is by far my favorite binder brand for many reasons.
1 month update: it still works well. Am happy with my purchase.
I get freckles when I'm out in the sun but these are the kind that are bigger and don't go away. Got some in places that aren't exposed to the sun like beside my belly button and my on my upper thigh.