Foamtreads - Cozy Sole- Men's (Black) - Men's: Slip into warm comfort. Soft fleece upper lined with organic Buckwheat. Organic Buckwheat seeds have natural heat transferring property. The loose seeds molds to the foots contours, allowing for maximum heat penetration and coverage. Tonal faux shearling lining collar that can be left up or folded over. Lightly padded for comfort. Fleece sole for flexible comfort. Heat in the microwave for no more then 60 seconds. The heat will last for over 30 minutes.