Non-toxic cooler gel pack out performs ice and other gel packs. Originally designed to keep blood shipments cold, these packs have as much energy as a freezer! Packs are designed to phase-change at 18 degrees (go from solid to liquid). This releases the largest amount of energy at freezer temperatures to get your food and beverages cold quickly. Put them in the freezer at zero degrees (typical freezer temp.) for 24 hours and you will have portable cooling power that actually accelerates cooling (cools things down rather than just maintain temperature) It last all day (24 hours) under constant use and opening and closing of your cooler. Great for fishing, boating, parties and tailgating. Add room temperature drinks and beer to your cooler and drink them at near freezing temperatures a few hours alter. Drinks and beer should not be left in direct contact with ice packs for a prolonged period as they will freeze.