CAN YOU HELP I AM WORRIED ABOUT THE FRIO WALLETS IF THEY ARE IN A NORMAL BAG IE RUCKSACK TO LET THE AIR CIRCULATE WILL THEY STILL WORK? AND DO THEY MELT AFTER A FEW HOURS? NEED TO KEEP INSULIN COLD FOR ABOUT 8 HOURS IN A HOT PLACE. THANKS NOT USED THEM YET ALWAYS TAKE A BIG COOL BOX BUT HAVE THE...