Say hello to cozy toes.

The Hotronic S4 Custom FootWarmer allows you to enjoy warm and cozy toes anywhere, anytime. The two included battery packs utilize cold weather-ready NiMH AA cells that yield up to 21 hours of heat. The two heating elements are compatible with any shoe, hiking boot, ski boot, or snowboarding boot thanks to the included self-adhesive covers and strips. 

  • Two battery packs
  • Recharger
  • Two heating elements
  • One pair of self-adhesive covers and strips
  • Reviews
  • Q & A

Keeps your feet warm all day long

  • Familiarity: I've put it through the wringer

These things work incredibly well but you have to be willing to make a small cut in your boot liners, which is not always ideal. overall, they are awesome, but if you're a snowboarder - it is a pain to figure out where to put the battery packs - they don't sit well on the back of the boot because your bindings will inevitably knock them off. I've ended up duct taping them a few times just to avoid losing them on the mountain.

so.. overall - functionally PERFECT. but the battery pack is bulky and easy to lose (and very expensive to replace)

I'm just trying to figure out what the difference is between the custom and universal versions?

Hi Brandon,

The Universal includes a pair of Heat Ready insoles while the custom does not.

Check out: for more info!


Does the red material have anything to do with heat distribution? I am going to use the warmers in an AFO (ankle brace). Being made out of plastic in gets cold and stays cold. Having polio years ago has left me with no calf muscle in my right leg. I wear two pair of stockings between my leg and brace, mainly for moisture absorption . Also I am quite active and this barrier also prevents any chaffing. Thank you for any info you could provide. I understand this is somewhat of a medical condition and any advice is closely scrutinized. I have had this condition for 66 years so I am more knowledgeable than most health care providers.

Thank You,

Thomas Ascroft

The red material is just a foot bed, and does not provide any heat. The green disc shown in the picture is the heating element. It would a be relatively small area of heat if you were looking to cover an entire AFO. You would probably be better off with a heated sock as long as the wires in the sock did not press between the AFO and your skin. It would be best to still wear 1 or 2 pair of socks underneath those to help cushion.

Best Ski Related Purchase.

  • Familiarity: I've put it through the wringer

I bought a set of these 2 years ago and it changes everything. These make 8-4 days of skiing easy, and quite enjoyable. They don't make your toes hot (unless you need a boost and hold the + button down until the lights blink, the batteries will then go on max until the battery dies) they just make them never get cold. Plus I can take mine out in say March when I wont need then anymore, and put them back on in January. These things are awesome.