No Battery Needed: No charger needed! Just put this neck cooling tube into ice water. Don't worry! It can be freeze with any air conditioner! Car air conditioners, office air conditioners, home air conditioners, ice boxes, refrigerators, and freezers. 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! New Coolant: new coolant, no condensation! (Dry and cool) Physical Cooling: Physical cooling, and more . 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. Features: The characteristics of the cold neck ring: The liquid inside is mainly liquid. The product can be used directly in contact with the skin after being freeze in the refrigerator. The surface will not be fogged or water droplets, and the temperature is always maintained at about 18 degrees, which is very comfortable to wear! If ordinary water is put in the refrigerator and then taken out, it cannot be used directly in contact with the skin, and it will be very cold! Our cold neck ring is made of a special liquid that is very comfortable to wear directly in contact with the skin! Colour:green Material:pcm phase change material Size:Outer diameter 115mm, tube diameter 2.5cm Package Contents: 1 * Neck Cooling Tube Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.