The WARMERS are provided vacuum, since the combination of ingredients with the oxygen present in the air causes the heat radiating through a chemical reaction of oxidation. Applied in the appropriate pockets provided with the band, make Khu an indispensable aid for anyone who needs to heat the neck and head, at any time of the day and in any place. Khu respects the environment, and does not require electricity to operate! Once finished using, the WARMERS can be safely disposed of as unsorted municipal organic.