1、Made of food grade silicone, safe and recyclable to use. 2、Wide mouth design, easy to fill up water without splitting. 3、Can be heated by microwave oven(2-3minutes), no electricity and charging needed. 4、Can also be used as a ice bag by putting it into refrigerator, which can serve as a cold compress for pains, sports injuries, fever and reduce swelling. 5、Comes with a knit cover, easy to storage and carry. Features: Made of food grade silicone, safe and recyclable to use. Wide mouth design, easy to fill up water without splitting. Can be heated by microwave oven (2-3minutes), no electricity and charging needed. Can also be used as a ice bag by putting it into refrigerator, which can serve as a cold compress for pains, sports injuries, fever and reduce swelling. Comes with a knit cover, easy to storage and carry. Specification: Material: Silica gel Color: Gray / White / Pink / Blue(Optional) Capacity: 525ml / 340ml (Optional) Size: L: 24* 9.5*5cm / 9.4* 3.7* 1.9 inch(Approx.) S: 15.8* 10.5*5cm / 6.2* 4.1* 1.9 inch(Approx.) Package list: 1 * Heating bag 1 * Knit cover 1 * User manual