No Battery Needed: No charger needed Just put this neck cooling tube into ice water. Is there no ice around you Dont worry It can be frozen with any air conditioner Car air conditioners, office air conditioners, home air conditioners, ice boxes, refrigerators, and freezers. Safe and Enjoyable: Enjoy the cooling time of 4-6 hours indoors and 3-5 hours outdoors. The cooling time varies with the external environment. By maintaining an optimal cooling temperature, the new material has no risk of skin necrosis or frostbite. Long-lasting Cooling Tube: Get ready for the hot summer and the innovative materials developed to keep you cool. This gel freezes faster than water and lasts longer. Physical Cooling: Physical cooling, safer and more assured. Brand New Coolant: Brand new coolant, no condensation Dry and cool