Get ready for hot summer days and keep yourself cool with an innovative material originally developed for. This PCM gel freezes faster than water and lasts longer! (Only 10 minutes in ice water, 20 minutes in a fridge or air conditioner!) No batteries needed! No chargers needed! Anything below 18(64) will start to freeze. Simply place this neck cooling tube in ice water. No ice around? No worries! Ice will form with any air conditioner! Car air conditioner, office air conditioner, home air conditioner, fridge, freezer. Enjoy 40 minutes to 2 hours of . varies depending on external environment. By maintaining the optimal cooling temperature, there is no risk of skin necrosis or frostbite due to cooling. Colour:Green Material:TPU+PCM Package Contents: 1 * Neck Cooling Tube Only the above package content, other products are not included. Note: Light reflection 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.