So I just got one in the mail and the first time I tried it on it ripped 🙁 . It sits different then what the picture has.

I got the L and it fits like it was made for a child. It’s completely uncomfortable, yet does pull your shoulders back (by force, if anything). I’ll give it another shot but so far, this is a poor solution.

its okay I ordered An XXL. I’m a male 5′ 8″ tall with a chest 44 of inch it fits great and I think made well but its like a rubber band, so it really DOES not have much resistance to pull shoulders back. its more like a reminder to stand up straight. I did wear it over my t-shirt. something is better then nothing, I’m on the meddle on if i would buying it again .
i did not get mine from amazon one i got is made of thick rubber band thick threading and the back piece made of some kind of vinyl.

here is the chart i used to buy it.

*Small fits waist sizes 24″-28″
*Medium fits waist sizes 28″-32″
*Large fits waist sizes 32″-36″
*XLarge fits waist sizes 36″-42″
*XXLarge fits waist sizes 42″-48″