I have the Black Hawk copy of the Uncle Mike's IWB. Honestly I don't know which company made their version first, but the two are pretty similar.
Mine is a Blackhawk nylon Inside-The-Pants size 5 for my G27. I only use it as a cargo pocket holster, and for that it works awesome. I like how thin it is and how the muzzle end is closed - great attributes for a pocket holster.