Flame and Spark combo for subzero temps
"Brilliant modular system, works at subzero temps for 'comfortably' warm sleeping. The connection system with loops and toggles works but they can tear quite easily if moving about at night but there is good cotton material to anchor stitching repairs into. I may even stitch all them in with some loops as a preventative measure for increased durability. Another great feature, these are big enough for at least 6' 0" blokes. Most other bags are tiny and you can't turn over in them and they are incredibly difficult to even pull up over your shoulders at night and just aren't big enough. These bags have plenty of room, maybe because they are designed for military contractors to be sleeping with full kit on. You can turn over easily in the middle of the night and very easily have the bag well over shoulders when getting back in the dark and even have the full hood over if you forgot to put a hat on, in sub zero temps. With the hood up, I reckon this Flame Spark combo will be 'comfortable' for sleep down to maybe -8 to -10 or more, especially once thermal longjohns and hat are added in and a thermal ground mat will only assist further. The boots section in the bottom is great aswell, I don't wear boots in these but I do stretch my legs out when getting back in at night to extend the bag out fully and it is rock solid in the bottom, I don't expect it will ever need repairing. With the zip seam amendment I mention in the Flame review and maybe a more durable ripstop outer shell, this modular bag system would be five stars without out doubt. It's functional performance is absolutely brilliant, it's only these minor details that have stopped the full five stars. I would be happy with the extra weight that the amendments may bring, for the step up in durability but maybe others prefer the lightweight benefits that it currently has??"