I just received one and it works good. The clip does not interfere with the insertion of the mag into the pistol at all. It clips nicely into your pant pocket for easy drawing and keeps the mag up out of the junk in the bottom of your pocket.

Just a heads up, in pic's 2 & 3 they show it being used on the Shield's long mag with the grip filler piece in place. Mine won't fit unless I modify the grip filler by opening up the hole the rest of the way. I didn't see this written anywhere on their website so just a heads up in case you intend to use it on your long mag.