Be ready for a hot summer with innovative materials originally developed for NASA to keep you staying cool. This PCM gel freezes faster and lasts longer than water (Only 10 minutes in iced water and 20 minutes in freezer, or AC air ) No battery needed No charger needed Freezing starts ANYWHERE below 18C (64F). Simply place this neck cooling tube into iced water. No ice around you? No worries It freezes using any AC Car AC, Office AC, Home AC, ice box, refrigerator, freezer. Enjoy cool time for 40 minutes up to 2 hours. Cold holding time varies depending on the external environment. No risks of skin necrosis or frostbite through cooling by maintaining an optimal cooling temperature. 100% brand new coolant with NO condensation phenomenon (dry and cool) TPU fabric with strong sewing doesnt allow tearing or breaking Ergonomic design that has won the design award Experience non toxic fabric around your neck