Hi Bruce, I like the idea of the smart carts you have in stock. I recently got 2- 5 pks from another vendor. First few vapes were great, then I got the nasty taste of burnt plastic. Upon removing the cart from my atty I noticed on both side right where the "groove channel" is that it was litterally burnt black and melted. This was on a 3.7v riva using a reg 2.3 ohm atty. I figured I must not have aligned the u-channel with the bridge, so I tried another one... Same thing from it. Was there a change in materials from the first version when they went to version "2"? I can't tell you where the others actually came from since it was in a "grab bag" from a site that sells stuff from lots of different vendors. I guess what I REALLY want to know is have you had this happen with the ones you have in stock? Thanks...