SlumberSystems is no longer in business, and the Mummy has been discontinued. If you're looking for something new, check out the best cold weather down sleeping bags for 2020.
I recently stumbled into a private manufacturer who makes this fantastic bag. It packs down to about 30 cm, and weighs a mere 2 kgs. In addition it is much cheaper than any of the bags on the market.
The bag boasts a -48C capablity. I have tested it down to -22C, and was warm in my underwear!
On speaking to the manufacturer, he claimed his aim was to produce a bag that you can "sleep in anywhere." I suppose if you bought one of those Gore-tex bivvy bags, he would be right.
All in all an ace bag if you are going somewhere cold!
Temperature Rating: -48C !!!
Weight: 2 kg
Price Paid: £300