ICEMULE The ICEMULE Boss 30 Liter Softside Cooler - Ultimate portability. Ultimate ice retention. Ultimate ease of use. No wonder the ICEMULE BOSS is the ultimate cooler. You can finally have frosty cold beverages, hour after hour, day after day, mile after mile. Premium, multi-day ice retention paired with a best-in-class suspension system - plus tons of dry storage - lets you go the distance and rest assured knowing you’ve got the best backpack cooler ever made.