Fit Lunch Bags The Cooler Ice Pack is activated by water. Refill the pack with water and the ice crystal particles will expand. Once expanded, refrigerate the pack for about 2-4 hours before packing it into a lunch bag. Reliable Material The Ice Packs use coarse, expandable dry ice crystal particles, which provide a strong cold storage effect for reliable cooling. Use Simply When adding water, do not fill the pack to the top. Leave some space because the ice crystals in the bag expand as they absorb water and freeze. Used Repeatedly This Ice Pack can be washed and reused for ongoing cooling. It expands with ice crystals and provides long-lasting refrigeration. Use scenarios - School or work lunch: place one or more packs in the lunch bag to keep meals fresh and cold until mealtime. - Outdoor activities: bring during picnics, beach trips, or long drives to keep beverages and snacks cool. - Travel or errands: use in coolers when shopping trips or short trips require cold storage for drinks or snacks.