NEW TECHNOLOGY: Our cooling neck ring utilizes a property of the Phase Change Material and maintain at that temperature as it melts in order to keep you feeling cool in the hottest of environments.EASY TO USE: To enjoy up to 180 minutes of refreshing coolness, simply place the neck ring in the fridge or freezer for 20-30 minutes. Take it out after freezing and place it around your neck. Use multiple neck rings for longer periods of cooling.REPEATED USE: The neck ring shell is made with very durable material and can be used repeatedly by freezing it again every time it melts. Spots of extra shine may appear on the surface after repeated use, which is completely safe and normal.SAFETY FIRST: The materials we use are 100% toxin free and BPA free. The cooling ring is SGS tested to ensure that it is safe for the body, keeping you safe while keeping you cool.ONE RING FITS ALL: The neck rings design allows it to fit comfortably on people of all different sizes and is weighed just enough for it to sit snugly on the neck without causing any stress to the spine or fall off when you are in action.18 degrees Celsius or below will naturally freeze, and no matter how you freeze or refrigerate, the lowest temperature should be maintained at around 18 degrees Celsius,28 degrees Celsius or below will naturally freeze, and the lowest freezing and refrigeration temperature should be maintained at around 28 degrees Celsius