Made from extremely light eVent DV Storm 3-layer fabric, the Alpine Bivvy Bag is a truly minimalist bit of kit. Weighing in at around 470g and packing down to the size of a one litre nalgene bottle it tucks away into the corner of any bag without fuss. A two-way zip opens round the edge of the head-end, opening in a clamshell format for access.
The fabric is extremely light and, as a result, pretty fragile and although ripstop it is vulnerable to puncture. We managed to keep it safe during the test, but only by carefully choosing our campsites. To help durability the bathtub base is toughened with waterproof 70 denier nylon, but it is still worth brushing your chosen spot down for sharp grit or twigs. Lightweight gear always needs that little extra care however, so this isn't a criticism of the Rab.
Every night we spend in this bag is comfortable, with very little condensation building up inside at all. That is helped by a little creative venting of the main zipped access which opens wide over the very top of the bag. Being a two-way zip means there are plenty of options to leave a section open for breath to escape and fresh air to get in - and of course for some late-night chatting and star gazing when the day winds to a close.
There is a generous storm flap over the zip and plenty of room for even a winter sleeping bag to loft up properly - as the name would suggest - so this truly is a year-round option.
An excellent lightweight bag, the Alpine Bivvy is expensive but certainly worth it. The eVent fabric performs perfectly, with virtually no condensation on any of our trips so far, while that wide opening allows plenty of options for sleeping under the stars. The pack size alone makes it all worthwhile.
