Apparently I have way too much time and money (not really). I wanted to know which cooler hacks I was finding online were worthwhile. Not just anecdotal evidence (it seems to be better...) but get measured results. This IS NOT a comparison of different brands of coolers. This IS NOT a guide to keeping ice longer. The purpose of this experiment is to compare the effect of a modification to a cooler. Only one modifiction was made per cooler. One cooler was original and not modified. The Grizzly was added just because I had it. Here are the coolers: Cooler I: Igloo Profile 16 Quart Cooler Cooler II: Same as Cooler I (same color, etc.) but with Insulation added to the lid. (LocTite Tite Foam Multi-purpose expanding foam used for insulating the lid.) Cooler IRO: Same as Cooler I but with Reflectix covering the Outside of the cooler. Cooler IRI: Same as Cooler I but with Reflectix covering the Inside of the cooler. Cooler G: Grizzly 15 cooler. All coolers kept in indoors for more than 24 hours at a temperature of approximately 76-77 degrees Fahrenheit. All water bottles refrigerated. All ice from the same ice maker in the same freezer. 4 pounds of ice was selected because I had 5 coolers to test and only had room for 20 pounds of ice in my freezer. I had to gather ice for several days from my ice maker to get 20 pounds. I bought a bunch of ice trays so if I try further experiments I can load them up the night before and have ice by morning (I hope). First experiment I placed 6 water bottles and 4 pounds (64 oz) of ice in each cooler. I then put them in the metal shed in my backyard for 24 hours. Temperatures ranged from 72F to 90F. I removed what ice remained and weighed it. Cooler I: 3 oz Cooler II: 9 oz Cooler IRO: 16 oz Cooler IRI: 26 oz Cooler G: 16 oz Second experiment I placed 6 water bottles and 4 pounds (64 oz) of ice in each cooler. I then put them in the front yard in full sun for 4 hours. I moved them a couple of times to keep them in full sun as shade was moving their way. Temperatures ranged from 75F to 88F in the shade. I did not measure the temperature in full sun. Cooler I: 30 oz Cooler II: 37 oz Cooler IRO: 37 oz Cooler IRI: 39 oz Cooler G: 36 oz Adding insulation improves performance, no big surprise there. I really expected the IRO to out perform IRI, but I was surprised. Reflectix is a radiant heat barrier so I anticipated having it on the outside of the cooler would reflect the radiant heat before it got to the insulation. Apparently that's not how it works. If someone reading this has physics knowledge better than mine perhaps you can explain it to me. I was dissappointed in the Grizzly as I really thought it would significantly out perform the Igloos. It's still a fine cooler and has the advantage of being a bear resistant canister (not that I need this feature) and should be fairly water tight if it tips over, but it's ice retention was not really shining when compared to a modestly modified cheap Igloo. The Igloos run about $20 each, the mods may be another $20, but the Grizzly is around $130. So now I know. I'll be testing resuseable ice packs next.