Heated Insole System

Rechargeable heated insoles I bought for January commutes have a thin lithium battery embedded in the heel and a carbon fiber heating element that runs the length of the sole. On the coldest mornings they are the only reason I make it to class without stopping at a coffee shop to thaw out. The insoles connect to an app that lets you set temperature in 5-degree increments from 100 to 150 degrees Fahrenheit, and the battery lasts about 5 hours on medium heat. Smart placement puts the heating element under the ball of the foot and the toes where you lose heat first. The heel section stays unheated to save power. Insoles fit inside any shoe with a removable footbed and the charging cable is USB-C. Using the same cable for my phone and my shoes is a small convenience that makes me actually charge them every night. I admire that someone looked at the problem of cold feet and solved it with a product thin enough to forget you are wearing it. At $130 for the pair, that felt expensive until the first morning I stood on a train platform at 7 AM in 15-degree weather with warm feet.