Natural down remains the most efficient insulator for sleeping bags, but it has to be kept dry to retain its outstanding performance. While waterproof shell fabrics can be used to protect the down, these can cause condensation inside the bag, which itself can dampen the down and in turn reduce performance.
Sea to Summit’s new range of down sleeping bags use a combination of the very best down coupled with the very best shell materials. The down boasts a 850+ fill power, which basically means it can fluff up exceptionally well, and the more it fluffs up, the more air it can trap and the warmer it is. Hence the best down leads to the lightest sleeping bags as you simply need less of it.
But having great-quality down is no good if it gets damp. Sea to Summit solves this problem by using 3D NanoShell on the outside of the bag. This fabric is water-resistant and breathable to keep the worst of the water away from the down. But the important element of this shell material is the polyester 3D Barrier, which sits on the underside of the fabric and holds any condensation away from the down while it evaporates through the NanoShell face fabric. The result should be a dry and comfortable night’s sleep.
The trouble with all that wonderful technology is that it is all hidden away inside the bag. The feature I liked the most was the impressive anti-snag strip on the zip, which allowed the zip to work effortlessly without jamming.
I also liked the general comfort of the Sea to Summit Traverse XTII, thanks to the great hood design and easy-to-use drawcords. A nice additional feature is that the bag comes with a good compression sack, an oversized mesh storage bag and a cotton sack to protect the bag during laundering (very detailed instructions explain how to wash and care for this very special product!).
Outer fabric 3D NanoShell
Inner fabric 20d polyester
Construction differential cut shell with offset internal baffles
Insulation 95% European goose down, 850+ fill power
Minimum comfort rating -11 deg C
Packed size 22x34cm in stuffsack; 22x22cm compressed
Weight 1210g bag; 1395g including stuffsack
Made in China
Stockist details tel. (0116) 234 4600; www.burton-mccall.co.uk
The Sea to Summit Traverse XTII is an outstanding combination of features for those who really want (and can afford) one of the best sleeping bags money can buy.