Lorrie S.wrote a review of Hotronic Footwarmer S4 Universal on February 27, 2017
Familiarity: I've used it several times
The heating element cables break easily. My husband and I know they are fragile and have each gone through 2 elements this season alone. This is an old problem that has not been fixed. The element does not work well with custom insoles as it is a hard metal plate under the ball of your foot. The battery packs are improved and last all day.