Powerful Cold Storage: These freezer packs contain dry ice crystal particles for excellent expansion and cold retention, offering high capacity and long-lasting cooling. Leak-Proof & Durable: Made from thickened PE material, these cooler bag freezer packs are leak-proof, robust, space-saving, and easy to clean. Easy to Use: Simply add water to activate the ice crystal particles. Allow space for expansion, then freeze for 2-4 hours before using in lunch bags or coolers. Cold Insulating: Reusable and providing extended cold storage, these ice packs can also be used with air conditioning fans for a more frosty, cool air. Multiple Uses: Ideal for various cooling needs, including food preservation, air conditioning fan cooling, incubator preservation, breast milk storage, fish preservation, and pet cooling. Specifications: Name: Ice Crystal Box Material: Thickened PE Options: 1 pc, 2 pcs, 3 pcs Composition: Absorbent Resin Size: S: approx. 16 * 4 cm * 4 cm/6.30 * 1.60 in * 1.60 in; M: Approx. 19 * 6 cm * 4 cm/7.48 * 2.36 in * 1.60 in Solidification Point: -12 degrees Usages: Unlimited (unless damaged) Instructions: Add water once for repeated use. Applications: Food cooling, breast milk preservation, air conditioning fan ice crystals, care cooling, BBQ self-driving tours, refrigerated transport, etc.