Strong Cold Storage Freezer Packs contain dry ice crystal particles and coarse particles that provide good expansion, strong cooling performance, large capacity, and high energy storage for long-term cooling cycle use. Leakproof and durable, these freezer packs are made from thickened PE material. They are leak-resistant, sturdy, space-efficient, and easy to clean. Easy to use: Add water to activate. The ice crystal particles will expand, so leave space before sealing. After expansion, freeze for 2-4 hours before use in lunch bags or coolers. Designed for long-lasting cold insulation and reusable performance, these cooler ice packs help maintain low temperatures effectively. Ideal for multiple applications including food preservation, cooling for conditioning fans, incubator use, breast milk storage, fish preservation, and pet cooling. Specifications: Name: Ice Crystal Box Material: Thickened PE Available Quantities: 1 pc, 2 pcs, 3 pcs Composition: Absorbent resin Size: S: Approximately 16 x 4 x 4 cm / 6.30 x 1.60 x 1.60 inches M: Approximately 19 x 6 x 4 cm / 7.48 x 2.36 x 1.60 inches Freezing Point: -12°C Number of Uses: Unlimited (if undamaged) Usage: Activate with water; reusable after initial hydration Applications: Food refrigeration, breast milk storage, cooling fans, personal care cooling, outdoor barbecues, road trips, refrigerated transport