This is a neck cooler ring that can cool down just by putting it on your neck. It is convenient for preventing heatstroke by wearing a mask or accessories. You can wear it in hot everyday situations such as going out, walking your pet or working in club activities, and it will cool down your neck. This product uses the PCM nature that freezes naturally under 66°F (28°C), so it does not require charging or batteries, so you can use it over and over again. What is PCM: PCM is a new material called phase replacement, and it is said to maintain a constant temperature by absorbing and dissipating heat. Maintains a constant temperature even when ambient temperatures rise, so it maintains a lower temperature than your body temperature. [About use] When the outside air reaches below 86°F (28°C), it will start to freeze naturally. Keep it in a room with a cooler or a place below 28 degrees of air to make it unique. If you want to use it quickly, (1) Place it in the freezer for about 5 minutes or more (2) Put it in the fridge for about 20 minutes or more (3) Put it in cold water for 15 minutes or more.