You can heat them in the microwave too for hot therapy!I made some tubes about 4inches wide and 2-3 ft long out of old pillowcases, filled with uncooked rice, sewed them shut. I keep a couple in the freezer to drape around my neck, across my knee, wherever I need it cold. Lasts long enough to get me through the worst of a bad hot flash. Or good for a sprain.