Here's a quote of a review from 'Sharp' over at J.D. forums
(The Sheath:
The sheath is fairly standard, and fairly mediocre. However, it is an improvement over the RTAK-I sheath, which I head didn’t have a belt loop. This new model is made out of black ballistic nylon, and comes with a nice belt loop, MOLLE loops and straps, and two lashing holes at the bottom (the knife will flop all over the place without a tie-down). It also contains a very nice gear pouch for a sharpening stone, folder, flashlight, etc. That’s the good stuff…now the bad stuff. The kydex liner for the sheath seems tough enough, but there is no friction fit! This means that if you forget to strap the knife in (via a snap, more on that later) the knife can fall out. Also, because there is no friction to the sheath the knife also rattles…no good. The next problem is the snap closure, which does a fairly good job of holding the knife into the sheath when it’s closed. However, the snap frequently jams and won’t come open (Sharp: I actually haven't had too many problems with mine). This is a REALLY huge pain in the ass. You can tug on the strap until your hands get blisters, and it still won’t come undone. The first time this happened, I had not strapped my knife on yet, so I grabbed the sheath both hand, took the strap in my teeth, and strained my entire arm strength on it until it finally popped open. The next time it happened I had already put the knife on, so I had to use the false edge one of my other knives to pry the two halves of the snap apart. Imagine if had I been in an emergency, or in the military, and absolutely HAD to use my knife right then. I’d be in deep sh*t. Sometimes though, the snap works just perfectly, so I don’t know what makes the difference. Point is, if it could go wrong, it WILL go wrong, and probably when I least want it too. If you have the money, but a better sheath. (Sharp: Yes buy an Eagle Sheath or the Soft Sheath from TOPs Knives. However, there are ways to form the kydex. I'm sure all of you are aware that heat softens objects. Boiling.)
Edit- Thanks to WVHILLS for the info. Brought this in from a google search.