The Foldable Ultrasonic Dot Pattern Ice Pack for Lunch Box uses an advanced ultrasonic dot matrix design to provide you with an efficient and convenient way to maintain the freshness and temperature of your food. Whether you're having lunch at the office or having a picnic outdoors, our cooler bags have you covered. This cooler bag has a collapsible design so it can be easily packed away when not in use for easy portability and storage. Its compact size makes it ideal whether it's in your backpack, tote bag, or office refrigerator without taking up too much space. Our cooler bags are made from high-quality materials for excellent durability and leak resistance, ensuring your food won't leak or contaminate other items. The ultrasonic lattice design provides a uniform cooling effect, which can effectively extend the freshness and taste of food.