ThermaCELL released its wirelessly-controlled Heated Insoles in 2012, and I've been wondering about them ever since. A local store couldn't keep the things in stock last winter, yet I've also seen more than a few user reviews stating that they just don't work. Given that I live somewhere where cold toes are a common problem for several months a year, I really wanted to know what the case was ... and I figured that lots of other people would like to know, too. I got the company to send me a pair, in order to find out.

First of all, a bit about the product ...

Each water-resistant insole has an integrated RF receiver, a rechargeable lithium-ion battery, and a heating element that's located under the front of the foot. The batteries are replenished using an included charger – a complete charge takes about four hours from empty, and the charger lets you know when it's done by shutting off its green "on" light.

Unlike other heated insoles, a simple push-button wireless remote lets users switch between High, Medium, and No Heat settings. On High, a thermostat within each insole maintains an output temperature of 110ºF (43ºC), while Medium keeps things at 100ºF (38ºC). No Heat turns off the heating element – it's a handy feature, as it allows you to save battery life by only running the elements when needed, without having to pull the insoles out to flick their own power switches on and off.

Should you lose track of whether or not the insoles are turned on, blinking LEDs in the back of each one will let you know that they're powered up, and what mode they're in. Their battery life sits around three hours on High, and closer to five on Medium.

When I first went to use them, I discovered that although the insoles don't look particularly thick, they won't fit comfortably inside just any footwear – even if you do remove the existing insoles first. This was disappointing, as I'd been hoping to use them in my cycling shoes. Undoubtedly they do leave plenty of foot room inside some shoes, but I'd say that they're mainly intended for use in boots.

Once I got them in my boots, I decided not to kid around and set them straight to High. I tried them out over several days, during which the temperature got as cold as -18ºC (0ºF).

So, did they make a difference?

I have to admit, at first I could understand why some people would think that they don't. They're not much warmer than body temperature, so they're never going to leave your toes feeling satisfyingly "toasty." Your feet instead just feel neutral, like they do at room temperature, making you wonder if the insoles are making any difference.

According to ThermaCELL, though, that's the whole idea. If your feet were to get sitting-in-front-of-the-fireplace warm, they would sweat. That sweat would proceed to carry heat away from your skin, and ultimately leave you worse off than you were in the first place.

It took some different testing methods, but I was eventually able to determine that the insoles did indeed allow my feet to keep feeling "neutral" in situations where they would otherwise get noticeably cold. They're comfortable, too.

Time will tell how they make out against some of the really stupidly cold temperatures we get here (i.e: -35ºC/-31ºF), but at this point I can say that they're definitely up to the task for most places' more "civilized" winter climates.

My only real complaint, aside from the fact that I can't use them in my cycling shoes, is the buttons on the remote. They could easily be accidentally pressed when the unit is stuffed in a pocket or purse, inadvertently changing the heating mode. Perhaps a single sliding switch might work better.

Oh yes, and one other complaint ... it's too cold where I live.

ThermaCELL's Heated Insoles are priced at US$135, and are available in a variety of sizes that can be trimmed to fit.

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