Benefits and features cooling performance: ice crystal particles expand to preserve coolness and keep foods and drinks at ideal temperatures. Durable and long lasting: thickened PE material provides dependable durability for daily use and reduces the risk of breakage. Portable and space saving: compact design fits easily into backpacks and lunch bags without adding bulk. Easy to use: add water to start the expansion of the ice crystal particles, then freeze for about 2 to 4 hours to maintain low temperatures in your lunch box. How to use Step 1: Add water to initiate the expansion of the ice crystal particles. Step 2: Place the ice pack in your lunch box or cooler. Step 3: Freeze for roughly 2 to 4 hours before use. Specifications and compatibility Material: thickened PE Intended use: lunch boxes and portable cooling in bags or backpacks Performance: maintains low temperatures for food and drinks during daily cooling needs Use scenarios School lunch: keep sandwiches, fruit, and drinks cool until lunchtime. Office lunch or commuting: maintain beverage and meal temperature during workday transport. Outdoor activities: picnic or day trips to keep perishable snacks and drinks cold.