The cold is different because it cools in the refrigerator. The double layer construction of cotton and urethane allows it to cool down gently and gently. (Designed to be gentle and cold instead of sudden cold. The insulated aluminum sheet blocks heat from the outside and keeps the cold air from escaping so it maintains a moderate amount of coolness. Made of 100% cotton pile fabric with natural material. Comfortable to the touch, not sticky with condensation or sweat. The 4-layer frozen gel bag is easy to fit your neck muscles. Adjustable length (neck circumference up to 18.5 inches (47 cm)). Washable and hygienic. Reusable For work and leisure activities indoors and outdoors. Material: Cover (made in China): Cotton, urethane foam, polyester gel bag (made in Japan): Water, polymer absorbent resin, polyethylene insulation aluminum sheet (made in China): polyester (vapor-deposited aluminum), foam polyethylene; Product Size: Body Size (includes cover): W 27.6 x H 3.3 x D 1.2 inches (700 x 85 x 30 mm) (with gel bag and insulated aluminum sheet set); How to use: 1) Insert it into the cover so that it does not protrude from the opening. Cool (2)(1) and gel bags in freezer (until the gel is fully frozen). At least 4 hours or more The longer it cools down the longer the cooling power will be better.) (1) and gel bags should be cool separately. (1) Place in a plastic bag or other item to cool it. The gel bag can be laid flat or folded flat with a fold (weld part) to cool it. It may be damaged if it is stuck in snoring. (3) Put the gel bag into the cover (please put the gel bag to the very longest) Insert the gel bag so that it does not protrude from the opening so that the gel bag is completely hidden. Vertical for easy insertion (4) Thread it through a string and put it on. Adjustable position and length with hook and loop fastener. Keeps towel fabric from touching velcro. Pilling Note: The contents of the gel bag cannot be eaten. If you eat the contents, please take this product and package with you, and consult a doctor. Please do not use it while sleeping. If you experience any abnormalities during use, stop using and consult a physician. Please rinse with water if the contents of the gel bag gets in your eyes or on your skin. If you experience any abnormalities, stop using and consult a physician. Those with cardiovascular diseases (hypertension, hypo pressure, narrow, etc.), consult a physician before use. Please do not use if you are unable to judge it is too cold. Please do not impact the gel bag or expose it to sharp objects. The strength of the gel bag may decrease after prolonged use. Discontinue use if the gel bag has decreased elasticity, cracks or breaks. Please read other precautions carefully before use.