SAFE AND EASY TO USE: The wide mouth design prevents you from getting scalded when filling with water and makes it easy to quickly and safely pour water into your thermos without spilling. Note: Please fill in two thirds with hot or cold water. Hot and Cold Compression: Compared to traditional rubber thermos, recyclable thermoplastic, advanced thermoplastic retains heat for up to 8 hours and can also be used as an ice pack or water heating pack. Note, however, that this thermos is not microwave-friendly. Non-toxic, odorless, and harmless: Thermos for cramps are free of BPA, phthalates and other harmful ingredients. An uncharged thermos is easier to carry around. You can use them anywhere with confidence. Also a great choice for holiday gifts A good helper: Use a soft-cover hot water bottle to relieve dysmenorrhea, muscle soreness, and pain in various parts of the body. Keep warm in winter and cool down in summer.