<p>Keep milk ice-cold for lunch and longer, assuming you pour the milk into an insulated thermos style bottle. Those type of bottles, without the ice pack, will result in slightly warm tasting milk by lunchtime which is about 6F degrees warmer than the fridge. With the ice pack, the milk will be true ice-cold! These ice packs were designed to be the optimal size for a 12oz drink to be kept ice-cold for lunchtime in a thermos. A larger size of ice pack means less drink volume, and a smaller ice pack would not keep the drink cold long enough.</p> <p>Instructions for best results: Put Ice Pack in freezer overnight. Place Ice Pack into insulated water bottle or thermos. Fill bottle with cold drinks from the fridge. The Ice Packs were not designed to be used in plastic, non-insulated water bottles. They work similar to ice, since that is exactly what they are. </p> <p>For 12oz or smaller bottles, use 1 Ice Pack; for larger bottles use 2 Ice Packs.</p><p>Expected performance - If the Ice Pack is placed in an insulated bottle that claims to keep cold for 12-24hrs, and chilled drinks are added, the drink will be kept ice-cold or refrigerated (between 34F-40F) for more than 8hrs. </p> <p>The Ice Pack is the same size as 2 ice cubes. It is not magic, but it will keep drinks ice-cold when used in a thermos. </p> <p>Water Bottle Ice Stick Dimensions: 4-1/8 inches long x 1-1/16 inch diameter (10cm long x 2.5cm diameter). Weight: 1.8oz (54g). Volume: 2oz </p>