We're working out what we think - we'll add our view here!
Sea to Summit says:
Offering the perfect backpacking balance of comfort vs weight, our Altitude™ Series sleeping bags have more space than traditional mummy bags, yet still provide the thermal efficiency you need when exploring above the tree-line.
The Free-Flow triple-zip design ensures your sleeping bag retains maximum warmth and efficiency when needed and multiple ventilation options when it’s not. The half zip on the left side of the bag provides freedom of movement for both arms, additional ventilation and also means the top third of the bag can be folded down as a mini quilt. The full length, two-way right side zip and separate foot zip transforms the bag into a full quilt for when the mercury climbs higher than expected.
If it’s warmth you’re after, close all the zips, pull the cord locks tight to drag everything in, and relax in luxurious comfort. The generous allocation of high quality 750+ Loft down ensures great insulation, while the oversized draft tubes prevents your body heat escaping. The panelled footbox and 3-dimensional hood make sure you’re not compressing the down when you’re trying to stay warm. The Altitude™ also features extra down overall and THERMOLITE® panels under the foot area, to help keep heels and ankles warmer.
Vertical baffles over the chest section ensure the down insulation cannot migrate or shift to the outside of the bag during sleep, creating cold spots. A side block baffle construction maintains the 60/40 fill ratio, keeping more down on the top of the bag for maximum insulation.
Our tapered rectangular design gives you additional wriggle room inside the bag, perfect for a side or restless sleeper and an alternative if you find a traditional mummy shape too constricting. The women’s specific fit is wider at the hip and narrower at the shoulder and comes in two lengths.