Kumfy Koatz - Cool in Summer, Warm in Winter Unique dual-action product combats extreme hot or cold weather Back strap sized to maximize contact for the Kumfy Pax in core area that regulates temperature. Neoprene material provides thermal properties including maintenance of heat and cold. Kumfy Pax gel pack is non-toxic, reusable, and replaceable. Back strap sized to maximize contact for the Kumfy Pax in core area that regulates temperature.