At first glance the Sea to Summit Micro Mc II (and it's slightly beefier sibling the... wait for it... Mc III) are much like most of the top of the range competition. High quality high fill power (850+ i.e. as good as it gets) European goose down - tick, superlight inner and outer (in this case impressively water resistant) fabrics - tick, baffled construction to make sure the down works as efficiently as possible - tick, ridiculously tiny weight (550g) and compressed pack size (2.5 litres - think melon) - tick, slightly scary price tag (£300ish)... tick.
So far so good, but what's new? Some years back some bright spark either on the mountainside or in a design workshop somewhere while contemplating how to shave a few more grams off sleeping bags had a bit of a brainwave - do you really need a zip? Cue adventure racers etc. wriggling caterpillar-fashion into their bags for the night.
All well and good, but with one downside - the warmth of the bag is the warmth of the bag, with only limited temperature control afforded by tightening or loosening the collar as much as possible. While not really a problem for adventure racers and alpinists - who tend to suffer from underestimating the cold more than excess warmth, it is perhaps not so great for more general users or those seeking a bag with as much flexibility of use as possible. Of course, lightweight bags didn't all go zipless - many designs still feature full or half-length zips, but in the Mirco series the Sea to Summit designers have put their zip thinking hats on the other way around and come up with a very neat idea.
"In the Mirco series the Sea to Summit designers have put their zip thinking hats on the other way around and come up with a very neat idea..."
The Micro bags feature a novel design consisting of a right to the bottom of the bag zip, with the bottom of the bag not stitched up but instead closed or opened up as desired by a drawcord. This arrangement not only allows for ventilation at both ends, but also by opening the zip completely and releasing the foot drawcord for the whole bag to be opened up and used duvet style. This might not seem all that much, but in use this flexibility has proven extremely versatile without compromising its basic sleeping bag function. First, it greatly expands the comfortable temperature range - from warm summer nights (15-20 degrees C) in duvet mode, down to 5ish degrees all zipped and draw-corded up.
"First, it greatly expands the comfortable temperature range - from warm summer nights (15-20 degrees C) in duvet mode, down to 5ish degrees all zipped and draw-corded up."
Second, the duvet version makes a great 'extra' throw on layer (in traditional blanket fashion) for lounging around camp or anywhere else for that matter. On a less luxurious front, bespoke two person huddle together sleeping bags/blankets have been successfully used by some elite weight scrimping alpine/adventure racing teams over the years (e.g. Haley and Westman on Denali Diamond), and although not yet put to the test, the Micro is a very promising summer-weight 'in the shop' option for such activity - e.g. as a shared blanket for a shiver-session on a long summer alpine rock route.
Other than the for most of us trivial (I estimate around 50 grams) weight penalty of the zip and drawcord, the only downside is the slightly tighter foot area in sleeping bag mode - the drawcord limits the boxy foot shape a bit. The only other minor criticism is that neither the head, nor foot end (less of an issue) drawcords are one handed - i.e. have the toggle attached to the bag so pulling the cord tightens the closure - easy enough to remedy in the next version?
A few other features are also worth a mention. The sleeping bag has a relatively snug fit around the body – minimising dead air space. The anti-snag strips (stiffened fabric) alongside the zip work very well at preventing the silky fabric from catching in the zip. The bag features a convenient (and so neat as to be almost invisible) integral pocket - for watch, phone etc. - just inside the head end opening. On the outer there a several hanging loops making drying/airing easy and the black inner also speeds drying in the sun. Last, as well as a neat and effective compression stuffsac (actually in the case of the Mc II a tiny bit oversized - a lightweight bivy bag could also be fitted in at full compression), the bag comes with a handy large mesh storage bag, and a cotton bag for use in washing.
A high performance lightweight down bag with a novel full length zip and foot-end drawcord feature allowing opening out to a duvet, enabling very flexible use both when asleep and around camp. A very strong performer for mountaineering, hill-walking, adventure racing, cycle touring, travel and any other warmer weather activities where a lightweight, compact and versatile sleeping bag is needed.
I've been climbing for a bit over ten years, and am currently based in Edinburgh having escaped from the southern flatlands. Climbing highs include Scottish winter climbing, a couple of trips to the Alaska Range, classic alpine routes, sunny ski touring, cragging in the UK and abroad, and beers and craic in the pub afterwards. Lows include Scottish winter climbing, alpine bivies, base camp blues, midges and the UK weather... I guess I'd like to be a jack of all trades and I'm definitely a master of none, but most enjoy the great variety of climbing and look forward to trips back to old favourites and hopefully many new and different places.