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  • Designed for use with Hotronic Heat Ready Insoles (sold separately) or on custom insoles, orthotics, or insoles of one’s own choice, creating custom-warmed footbeds
  • Installs in all types of footwear, and transfers easily from one pair of footwear to another
  • S4 comes with all you need to customize your ski, snowboard or hiking boots using insoles of your choice
  • Kit includes 2 battery packs with heat regulators, 1 recharger with American and European adapters, 2 heating elements and 1 pair of Cambrelle covers and strips
  • Features 4 temperature / durations settings, including a timed setting for an extra blast of heat
  • Setting level 1 heats from 84° to 98° F (29° to 37° C) for 16.5 - 21 hrs.
  • Level 2 heats from 107° to 121° F (42° to 49° C) for 7.5 - 10 hrs.
  • Level 3 heats from 122° to 138° F (50° to 59° C) for 5 to 7.5 hrs.
  • Level 4: 158° to 173° F (70° to 78° C) for 2.5 to 4.5 hrs.
  • Level 4, which can be used in 3-min. intervals or continously, is meant for a burst of heat; CAUTION: Using longer may result in burns
  • Battery pack LEDs indicate whether power is on or off and selected heating level; lights blink when heating level 4 is selected to run continuously
  • High-capacity, rechargeable batteries are designed for cold-temperature operation; battery packs attach outside for easy operation
  • Batteries maintain up to 55% of a full charge and 95% of the initial capacity after 4 years of non-use


View all Hotronic Hand and Foot Warmers

REI membership


Best Use Snowsports
Material(s) Unavailable
Dimensions 15.5 x 9.25 x 2 in inches
Weight 2 lbs. 0.8 oz.
Rated 1 out of 5 by from Dead After One Season 1 out 5 star review since the product uses battery technology that if they go completely dead they don't turn back on. For the couple times used before putting them up last season they worked really good. To Bad they used that type of battery in a seasonal product, least here in WA. REI was understanding with the return though, thumbs up REI.
Date published: 2016-01-25
Rated 5 out of 5 by from Toasty Toes I've been using my Hotronics boot heaters for 8 years. Cold toes are what used to cause me to go in for a break. I can't tell you how much I appreciate my Hotronics. I appreciate my toasty toes everytime I hit the slope. A great investment.
Date published: 2015-02-13
Rated 5 out of 5 by from Saves My Ski Day I have had these for years and they really have saved me on the coldest of ski days. When it is negative out on the mountain, I've learned to make sure they are on and my boot is warm before going out. They won't heat the boot when it is starting at a negative temperature.
Date published: 2017-01-19
Rated 1 out of 5 by from Extremely useless Why did I buy that junk...? I had a hope, when -40'F will come my feet will be nicely toasted with heat coming out of that junk. I do work outside every single night, we had minus 30'F on the clock last shift, OH GEEZZZ!! there is nothing but useless Hotronic. Closest REI store is about 300 miles away.. The very next time I am home I'll dump that useless junk over the counter. Is there everyone who can tell me what really works under my feet during such brutal winter
Date published: 2015-01-08
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