Posture Correctors

I saw this thing:

http://www.posturenow.com/#

On a Shark Tank rerun, and given chronic shoulder pain and chronic advice from my doctor to fix the posture that contributes to it, it seems like a useful device.

Regrettably, it appears to be shoddily made–2.5 stars on Amazon, with a number of complaints of poor manufacture.

There are, however, dozens of similar braces serving similar posture correction roles. So, I turn to the dope. Who’s used these posture correctors? Which ones are effective, which ones should I avoid?