If you hunt in the north, late in winter or anytime in high mountains, you will at some time need some means of keeping your hands and body warm.  Hand warmers and other body warming devices have been around for a long time, but all have their limitations.

Are you a ground pounder like me?  I get nervous climbing on a chair to change a light bulb, let alone climb a tree to hunt from a tree stand.  Now, I didn't say I don't hunt from treestands, but now you understand the risks I will take on my life to do so.  But as a rule, I would rather take my chances on the good ole earth.