cooler shock 4 mid size cooler freeze packs 10"x 9" - no more ice replaces ice & reusable. you add water & save! cooler shock non-hazardous cooler gel pack made in the usa, (not a chemical copy from china or taiwan) food safe. outperforms 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 for 12-24 hours (depending if you stack them) and you will have portable cooling power that actually accelerates cooling coolershock is shipped to you dry. simply add water, zip it closed and permanently seal with an iron or screw the cap on. easy instructions included or check video. pack turns to gel in 15 minutes. it lasts all day (24 hours) in size-matched coolers listed at our website. great for fishing, boating, parties,and tailgating. add room temperature drinks to your cooler and drink them at near-freezing temperatures a few hours later. drinks should not be left in direct contact with ice packs for a prolonged period as they can freeze. great reviews, what about the bad reviews? all ice packs have a limited life span depending on the number of times you freeze them. they all eventually split from the freeze thaw process. cooler shock pays for itself in about 5 uses (ice you didn’t buy). cooler shock can cycle (freeze-thaw) 80 to 300 times, depending on if they are getting knocked around a lot while frozen, or if they are mixed in with sharp objects. some users use them every day. that is a lot of cycling! for such constant use, we added the 8 mil sport clear bags as an accessory. this helps with commercial use as well. also, in 2018 we converted all of our bags to the 8 mil nylon coated type. we increased durability 50%. our 1-year guarantee – if you have any issues at all, contact us directly for free replacements. we are easy to find, and we are very responsive. details are on our website at coolershock.com since 20