- Excellent Expansion: This ice crystal box contains coarse dry ice crystal particles that expand effectively, providing superb cold retention, a large capacity, and high energy storage for prolonged cooling and circulation. - Durable Material: Made from reinforced PE material, this product ensures long-lasting stability and break resistance, making it ideal for regular use in lunch boxes to reliably keep food cool over extended periods. - Perfect for Lunch Packs: After filling the particles with water, let them swell in the refrigerator for 2-4 hours before use in lunch bags or other applications. As the ice crystals expand when frozen, be sure not to fill the bag completely to allow for adequate space. - Exceptional Cold Preservation: This product can serve as ice crystals for air conditioning fans, enhancing the cooling mechanism to produce crisper cold air. It offers super long-lasting cold preservation and can be reused multiple times. Use Cases: 1. Ideal for keeping lunch fresh during long work hours or school days. 2. Perfect for outdoor picnics and camping trips where perishable food requires reliable cooling. 3. Suitable for enhancing the performance of air conditioning systems to optimize cooling efficiency. Designed for optimal performance, this ice crystal box is your solution to effective and efficient food preservation and cooling needs.