I have a bad back and this helps prevent back soreness and strain.  It can be worn over or under clothing and fits a 32" (and probably a 34") waist or smaller.  It is a big help with my posture when using a compute for long periods which is a problem for me.

It provides a light support for the back but isn't in the same league as the leather or heavy support belts for construction or weight lifting (or cost or discomfort either).

Can be a little fussy to adjust and I find the suspenders to be a determent which is why it gets a 4 (even if you remove the suspenders it is fussy to adjust).