Sea to Summit Micro MC II

2-3 season bag that's easy to pack and carry, and is very flexible in use, covering a huge range of above-freezing temperatures.

I used this bag in early 2013 on a 3-month cycling tour of Australia in summer/early autumn. I moved to a new location most days, so there was plenty of packing and unpacking. Conditions ranged from around +2°C (ground frost) at 1,000 m in Tasmania to + 30°C night temperatures at sea level in southern Queensland. I always use a Coolmax liner as it's much easier to wash a liner than a down bag. (I find silk liners to be too clammy.)

In the coldest temperatures I was snugly warm in a lightweight merino cycle top inside the liner and with the bag zip fully closed with hood up and foot end closed. A bit warmer, and I dispensed with the cycle top and hood. A bit warmer still, and I opened up the foot end. Even warmer, I only partially closed the side zip. Warmer still, I opened up the bag fully and spread it over the liner, like a quilt. At the warmest, I started off with liner only and dragged the quilt over me if I got chilly later on in the night.

I'm 1.78/80 kg and the regular size was fine for me. The full zip makes entry/exit very easy. Unlike earlier versions (judging from other reviews), my 2012 bag had a narrow but adequate draught-excluder inside the zip.

The bag is very light (approx 600 g in its compression bag) and can compress down to approx 2 litres if you really try. However, I usually stopped at between 4 and 3 litres because I found that the bag puffed up much quicker when not compressed to its limit. I had no prolonged periods of rain (lucky me!) so can't comment on moisture resistance.

The bag IS very light, and like all lightweight products you must exercise reasonable care if you want it to last. Having said that, I've now spent more than 100 nights in my bag and packed/unpacked it almost as many times - and it still looks and performs as new.

I can thoroughly recommend this bag if you want something that works well over a large temperature range down to near freezing. If your expected temperature range is a bit lower, or if you're a woman, then the slightly thicker MC III has exactly the same design and flexibility, and is a bit warmer.

I had forgotten how clever I thought this bag was.

It is meant to be light, so don't complain about what it lacks but they try to compensate in other ways. They have just tried to leave the essential bits.

The zipper baffle is stiffened just enough to stop it snagging.  

It lacks a box foot to save weight... this allows you to open it completely like a quilt and vent the foot end of the bag but you may have to hitch the hole under you on truely cold nights.  

The stylish black inner is I assume to allow the unfolded bag to warm in the sun the next morning to lose condensation.  

The bags weights are printed inside with suggested temperature comfort zones. It came with a compression sack and a loose storage sack and even a sack designed to wash the bag in and drying loops in the right places. I am yet to find myself too hot or wet in it.

Yes, it is starting to look older and heavier (eg. the S2S Spark series are lighter and cheaper but might be hard to keep cool in).

It was expensive when released, but it is usually on a significant discount somewhere.