On a mid-level trek you are likely to encounter night-time minimums of -5°C and sometimes lower. On milder nights the lightweight Minim 400 bag will be enough on its own, but when temperatures fall to -10°C or below, it’s no problem with this System. Slip the Filler bag inside the Minim and it will extend the capability of the Minim 400 from -5°C to -15°C.
The Filler bag does offer advantages of its own. If parts of your trek are in warmer areas, the Filler is rated to +15°C as a stand-alone bag and would probably remain comfortable at close to +20°C, offering an option for warmer nights. It can also act as a good alternative in teahouse or lodge accommodation on nights when you're not camping.
K Series:
The Minim 400K Down Sleeping Bag is available in the K Series: performance is the same, but the exceptional loft of 1000 down reduces the weight of the bag to an amazing 585g (21oz).