Not a bad holder, but it has some issues:
1. Mag retention isn't great, even with the mags it's designed for (Glock, in my case). Don't expect to do a lot of jumping or running or scuffling and have your mag stay seated.
2. No adjustable tension, which means that it will not work with thinner mags. For example this one, made for the 9mm Glock mags, is far too wide for 9mm M&P, XD, or Sig mags. Fobus does make holders for these brands, but it would be nicer to just have a design that worked with multiple mag types so I didn't have to buy a separate holder for each.
3. The paddle doesn't seem to lock solidly to your belt and can slip off easily; also tends to migrate around (at least it did on my duty belt). Also, 1.75" belts are a bit too wide to fit well.
Summary: I guess it works for training, but I cannot recommend it for duty use. For the money I'd absolutely recommend that you go with single mag holders by either Safariland or Blackhawk(both available here on Opticsplanet).
Pros: Good price, seems well made, works with either right or left side carry
Cons: Poor retention, only usable with 1 type of mag
This review was written in the old system and had content requirements that are different than reviews written today.