I used the Tenzing waist pack with handwarmer (also referred to as a fanny pack, bum bag, ket bag, or hands-free belt satchel)  last year and was very impressed and almost give it two toasty warm thumbs up. The design is very well thought out and very efficient in the field. I used it still hunting in tree stands, from ground blinds, and in enclosed blinds. I used it as a primary pack during some midseason short hunts and as a secondary pack for longer hunts.  The functionality of having adequate storage at my fingertips along with a handwarmer allowing me to not use gloves, that I avoid as much as possible, is ingenious. Not to mention the multiple pockets designed specifically for heat sources such as Hot Hands or the Zippo handwarmer.  The only downside and reason it almost received full merit was the phone sleeve on the top. Don’t get me wrong, this is another great feature and well thought out. Put the phone directly on top where it can be viewed without removing it, use a sleeve that allows the touch screen functionality, and then put a flap on it so that it can be covered up in low light conditions as to not disturb any game if it is activated. My disappointment is with the size. I have a regular size smart phone, not one of the tablet wanna-be’s, and even with the case off it will not fit completely in the sleeve allowing the Velcro to close. My final thought is that Tenzing give a raise to all the people on their R&D team so that they can upgrade from the IPhone 3.  If David Allan Coe almost wrote the perfect country and western song, then Tenzing almost made the perfect waist pack with handwarmer!