The newer model ski boot heaters have small battery packs that are easily and quickly rechargeable. Most can be recharged without being completely drained and will be ready for a full day of skiing well before morning. These heaters can be adapted to boots used for other winter activities, such as hiking, snowshoeing, hunting, and for use in work boots.
Cozy Feet, Hotronics, and Therm-ic are some of the companies that make the most popular selling foot warmers available today.
Most brands have brackets that allow the battery packs to be mounted on the back of the ski boot or secured to the power strap on the side of the boot. Ray Rice suggests that even though the boot-mounted bracket seems more secure, there can be issues with low chairlifts and stairs banging the boot-mounted pack, so he recommends the side strap mounting.