Keep your feet warm with Grabber Foot Warmers providing 5 plus hours of heat. Air activated. Just open package and place in your shoe or boot to activate heating. When done, dispose in trash. Environmentally friendly. Size Medium/Large fits Mens shoes 8 Plus and Womens shoes 9 plus. Also available in Small/Medium sold separately.Specifications and Features:Just open package and put in your shoe to boot to activate heating.Provides 5 plus hours of heat.Environmentally friendly, non-toxic, all natural ingredients.