A slight word of caution. According to the manufacturers data the indpendent test performed by Leeds University gives the Blizzard Bag a TOG rating of around 8. This would be equivalent to a summer bag i.e a 0.8Kg good down mummy bag. According to the EN13537 specification this would equate to a lower limit of comfort of around +3 degrees Celcius and an extreme temperature rating of around -5 C to -9 C. (serious risk of death through hypothermia) If your going to use the Blizzard bag as intended in real world i.e lying on your rucksac then I seriously doubt that the bag will be able to cope with any temperatures below freezing i.e. 0C for any extended periods i.e. greater than 3 to 4 hours without a suffering a cold weather type injury. If your meat locker is at -18 C then I would be be surprised if you last more than a couple of hours at this temperature before being carted off to the ER to be thawed out. The name Blizzard bag is slightly misleading. Scottish mist bag would be more appropriate.