This holster we were issued to wear around the FOB in Iraq many years back when we were allowed to wear our diver shorts during down time. I scoffed at it and it sat for a while. I decided to use it, and now its for my everyday carry, it has been a gem, but different strokes for different folks.
It has two spots for your belt to loop through. The inner section the belt goes between your waist and the gun, not a fan personally. The outer loop the belt goes outside of the pistol allowing it to rest very close to your body. I carry an XD9 Sub, wear athletic cut shirts and I don't profile. The awesome thing about this holster is when I know I am headed to gun-UNfriendly spots or need to wear my other guns, it isn't gun specific so my LC9 fits, Governer fits, XD, Kimber 1911... all same holster.
It isn't perfect, but what is? I am also a Lefty, so slim pickin's anyway.
I do not use the button retention. My wife often tries to suprise me at home by trying to pull my gun out of the holster. The belt on the outside of the gun keeps it very tight. It has never fallen out, I often wrestle with my 85lb dog. Neither the dog or the gun leave my side.
http://www.blackhawk.com/product/Ambidextrous-Flat-Belt-Holster,319,34.htm