ThermaCELL's electronically heated insoles ($130; thermacell.com) aren't perfect, but they are the best cure I've found for my biggest late-season deer hunting problem: cold feet. When temperatures drop into the teens, my toes burn with the cold unless I'm wearing heavy felt-lined boots. If I have to hike to my stand or want to do some still-hunting, however, pac boots make my feet sweat, which guarantees my toes will be cold when I stop.
The best thing about ThermaCELL's heated insoles is the fob-like remote and built-in control board and battery. Unlike chemical toe warmers, which start out hot and gradually cool down, these let you wirelessly select "No Heat" when you don't need any supplemental warmth, then either "Medium" (100 degrees F) or "High" (110 degrees F) heat when you do, all without clumsy external batteries or switches.
That allows me to wear a favorite pair of lightweight, moderately insulated knee-high rubber boots when on the go, with the assurance that I'll be able to ramp up the heat if I take a stand or stop for whatever reason. And even if I'm wearing heavier boots, the control board acts like a thermostat and temporarily shuts off power to the heating element when it reaches the selected temperature.
It's genius--though not without a few flaws.
For starters, the molded, cushioned insoles are much thicker than the insoles that come standard with most boots. I can only use them with light socks in boots that are large to begin with. Otherwise the fit is way too snug.
They could also be a little warmer, and the battery life is disappointing. The lithium-ion unit built into the heel of each insole recharges quickly, but in my experience it does not come close to the advertised five-hour run time at medium heat. Of course, I could say that about my GPS and smart phone, too.
And they're pricey, at about $130. If the battery lives up to its promised 500 charges, that works out to only about $0.26 per use, which is about one-quarter what chemical toe warmers cost. At this point, though, that's still a big "if."
But my biggest complaint is with the remote. It doesn't confirm what setting the insole is at. Sometimes it's off when I want it on and on when I want it off. A positive on-off switch, or even better a setting and battery level indicator, would be a huge improvement. So for now I'll have to wait for the perfect cure. Until then, these are pretty darn good, and I'm thinking of buying a second pair so I can swap them out on all-day hunts.