Heat Factory Footwarmer Insole

The Heat Factory Footwarmer Insole is designed for use in the restricted air environment of a shoe or boot for up to seven hours. They are thin and comfortable and can be placed under a sock to provide soothing warmth underneath your feet. The Heat Factory insole contains a biodegradable mixture of iron powder, charcoal, salt and vermiculite that oxidizes when exposed to air to generate heat.