The question has come up about how chemical warmers should be used. The manufacturer recommends not putting them in contact with skin. Fortunately many gloves and mittens have a “pocket” where the warmers are meant to be inserted. There is a layer between the skin and the warmer in this case. Look at the Swany Gloves and Mittens and you'll see examples of these. Some people use a glove liner under their glove or mitten and also use the warmers. This will place a layer between the warmer and the skin. See the Seirus Outlast Glove Liner. For the toe warmers, they are placed outside the sock, usually under the toes.