ThermaCELL Heated Insoles ProFLEX Review

by Andrea · Published November 7, 2014 , 2:42 pm · Updated August 7, 2023 , 7:54 am

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ThermaCELL Heated Insoles ProFLEX

As a self diagnosed Raynaud’s sufferer I was more than ecstatic for the opportunity to test ThermaCELL’s Heated Insoles ProFLEX. I can simply walk out of my front door in 30 degree weather and my fingers and toes are white within minutes. Having poor circulation is not only a strain on your body; it really puts a damper on enjoying your favorite outdoor activities. I grew up in North Dakota so I know what cold is. In true North Dakota fashion, people just buck up and go outside, otherwise, NoDaks would just be indoor dwellers 9 months out of the year. But really we are not at all! We enjoy every activity in 0 to -40 degree weather as people in Colorado do in 30 degree weather. Fortunately for me, I no longer have to endure absolute frigid temps (well only when visiting), but now living in Colorado, I have become a little soft when it comes to the cold. I no longer can endure the -20 degree temps without 4 sets of hand warmers in each glove and 2 sets of toe warmers in each shoe. I should buy stock in hand/foot warmers! Well, hate to say it Hot Hands, my yearly purchases will be drastically decreased thanks to ThermaCELL!

ThermaCELL Heated Insoles ProFLEX

Initial Thoughts & Sizing

When my ThermaCELL Heated Insoles ProFLEX arrived I nearly ripped them out of the box. I was headed up to the mountains for a camping weekend that I was slightly dreading, since I knew it was going to be cold. When I initially took them out of the box I thought there was no way they could possibly fit in my shoes. They looked huge! My shoe size is 8 ½ and I received a size large which fits US & CA shoe size 8 ½-10. Thankfully ThermaCELL provides you with a trim option. There is a yellow line that you can trim for the perfect fit. I did notice that the insoles were rather narrow at the toe. I’m not sure about you, but I have wide feet so trimming the toe box down was a challenge. I did have to cut them exactly on the yellow line. It states that cutting past the yellow line may damage the heater and void your warranty. I achieved a perfect fit by removing my insole from my hiking boots, and followed that insole as a template. I was able to trim the Heated Insoles fairly close to my original boot insole. Being double the thickness as compared to my original boot insole, I was skeptical of the ProFLEX fitting in my boot. Because of the added thickness I did wear a thinner sock, but my boots have always been a little on the bigger side anyways.

With my Smartwool lightweight thin socks my foot rested comfortably in my boots with the Heated Insoles. In the information pamphlet, ThermaCELL does recommend wearing medium-to-lightweight socks that wick away moisture. A heavy sock may prevent heat from reaching your foot. My only con regarding the sizing is that I found the Heated Insoles to run on the larger side. If I were to get another pair I would go down to a size medium since I’m right at 8 ½, which is the beginning of the large size. I would also recommend going up a size on whatever boot or shoe you plan on wearing the insoles in. My boots were a size 9. The insoles did not fit in my 8 ½ sized boots.

ThermaCELL Heated Insole ProFLEX compared to my original KEEN boot Insole. Notice the difference in thickness?

Trim To Fit

Technical Features

ThermaCELL Heated Insoles ProFLEX are made from Polyurethane foam which allows the insole increased flexibility and breathability. The toe portion of the insole is quite flexible. It’s nothing like your boots or shoes original insole though. Those you can usually bend in half. The Heated Insole is stiffer, however it does move in all the right places. The heel portion where the battery lies is very stiff, but the foam padding provides enough cushion for lasting comfort. The removable rechargeable battery lies fairly flush with the insole. The battery is padded with Poron, an antimicrobial, shock-absorbing cushion. The Poron cushion is very cushiony, however, I was able to feel it on my foot wearing a lightweight sock. I wasn’t uncomfortable; I could simply tell there was a difference in materials underneath my foot.

ThermaCELL Heated Insoles ProFLEX with wireless remote and rechargeable batteries

ThermaCELL Heated Insoles ProFLEX come with a set of removable, padded, Lithium-Ion Polymer rechargeable batteries. Charging the batteries is a breeze. Included are a Smart Charging Case, one wall charger, and one USB cable. The USB cable is a fantastic feature because you can charge them on the go in the car! The first time I charged the batteries it took between 3-4 hours to fully charge. The Smart Charging Case LEDs flash green when fully charged. My Heated Insoles are now trimmed, charged and ready for action….bring on the heat!

Removable & Rechargeable Battery

ThermaCELL Heated Insoles ProFLEX come with a remote control with 3 options (No Heat, Medium, High). The green LED light in the rechargeable battery compartment will flash intermittently indicating the heat setting: one flash indicates No Heat, two is for Medium Heat (up to 100 degrees Fahrenheit), three is the High Heat setting (up to 111 degrees Fahrenheit). On the remote there is a light that will flash red indicating the battery has responded. I really like the feature that on the insole you can tell what heat setting you are on. However, you to have to take off your boots to actually look at the insole. I would like to see a light on the remote control allowing you to see the temperature setting.

ThermaCELL Heated Insoles ProFLEX Performance

I used my ThermaCELL Heated Insoles ProFLEX in my KEEN Oregon PCT boots (please see review). As stated before my shoe size is 8 ½, these boots are a size 9 and I’ve always had to wear a heavy sock with them to get a good fit. With the thicker Heated Insoles and a lightweight sock, they fit perfect. KEEN Oregon PCT boots are slightly insulated and lined with a breathable waterproof membrane. When I first used the Heated Insoles I started on medium heat. I would say it took approximately 20 minutes until I could tell the insoles were on and working. I quickly advanced my setting to high heat. It took about 10-15 additional minutes until I could feel the difference in temperature. I’m used to my Hot Hands foot warmers, which feel quite hot, bulky, and uncomfortable in your boots. The Heated Insoles eliminated all that.

It is important to note that they are designed to take away the chill. Your toes will indeed warm up, but it’s a slow and subtle warmth. Please do not expect your toes to be completely hot and toasty. If active, you are not going to want that anyway. With that said, after 4-5 hours of continued use, your Heated Insoles will feel quite warm to the touch. The heat source is at the front of the insoles by your toe box. The heel portion of the heated insoles does not warm up. I used my ThermaCELL Heated Insoles ProFLEX during a weekend of camping and on various hikes in approximately 30 degree weather. We have had a particularly warm fall so I have not been able to test the Heated Insoles in cooler temps. Ski season is on it’s way and the Heated Insoles fit in my ski boots, so I will update this review as cooler temps come my way! ThermaCELL Heated Insoles ProFLEX are manufactured to be highly water resistant. On my hikes the ground was damp, however, I was not stomping through puddles. It did rain lightly on one of my hikes and my feet stayed dry and comfortable throughout my adventure. My feet did not sweat because I kept my heat on medium since I wasn’t hiking in freezing temps. When I took off my damp boots the insoles were dry. The Heated Insoles can be used in fishing/hunting waders, so if anyone who is reading this review has used them in waders please feel free to provide a comment!

ThermaCELL Heated Insoles ProFLEX are flexible and provide hours of comfort for all your outdoor adventures

The Polyurethane foam provided great flexibility and comfort on long 7-10 mile hikes. My feet were able to move freely in my boots with the Heated Insoles. I felt the battery life was accurate at around 5 hours. It would be nice to have a longer battery life, but I found using the heat setting intermittently really worked well. Preserving the battery life was important to me since I knew I would be out in the cold longer than 5 hours. If only hiking for 3 hours I would keep the heat on the entire time. ThermaCELL does provide you with the option to purchase additional battery packs. If your outdoor adventures usually last longer than 5 hours, it might be worth it to purchase a second battery set. After 5 hours is up simply remove the battery which lifts out of the insoles with ease.

Who would benefit from using ThermaCELL Heated Insoles ProFLEX

ThermaCELL Heated Insoles ProFLEX are perfect for anyone who is outside in cooler temps. They can be used in your footwear for Hunting, Stream & Ice Fishing, Camping, Snowshoeing, Walking your dog around the block, Hiking, Skiing, or any outdoor endeavor you can think of. If you need shoes or boots for your adventure, you can use ThermaCELL Heated Insoles ProFLEX!

Happy Hiking!

Final Thoughts

The performance level of the ThermaCELL Heated Insoles ProFLEX is unlike any other. The flexibility and breathability make the Heated Insoles comfortable for all day use for a variety of adventures. The warmth and comfort the Heated Insoles provide on cold days make outdoor adventures enjoyable again! The ease and convenience of the Heated Insoles makes this my go-to product for this fall/winter season. No more bulky battery packs or stuffing my shoes with hot packs! With the wireless and rechargeable ThermaCELL Heated Insoles ProFLEX Jack Frost is no longer nipping at my toes! For more information on ThermaCELL Heated Insoles ProFLEX visit www.thermacell.com or www.amazon.com/thermacell.