3F Tyvek Bivvy bag.

It’s quite unusual for me to write about any product sourced directly from China. The reasons behind why I generally don’t write about such things are numerous and probably best saved for another day. However, as you may have guessed, I’ve mentioned that snippet because direct from China is exactly where this bivvy bag came from.

The hood features a nice red trim making it easy to find in a snow storm.

Tyvek’s great. It’s waterproof and breathable, it’s not too heavy and it’s fairly hardwearing but you wouldn’t want a bivvy bag made out of it would you? Well, you might if it were made from Tyvek ‘Soft Structure’ rather than the more usual ‘House Wrap’ variety. Tyvek Soft Structure shares the waterproof and breathability attributes of House Wrap but possesses the feel of material rather than the waxed paper, Izal toilet roll feel we usually associate with DuPont’s finest … Izal? Ask your mum.

Waterproof material but the zip isn’t and neither are the seams, so don’t expect ‘fully waterproof’ without modification.

I’ve long thought that Soft Structure would make a fine bivvy bag but until quite recently, no one’s done it but now they have, the results seem quite positive. 3F make lots of ‘outdoor stuff’ including tents, shelters, rucksacks and now, a Tyvek bivvy. The actual design is reasonably standard bivvy bag fare – a large hood with draw-cord but also, a half length zip running down the top from neck to waist, which does make insertion and extraction a little easier.

Just about big enough to house an air mat, winter bag and you.

Although I’ve said that Tyvek is waterproof, you shouldn’t consider the bivvy bag to be … firstly, the seams aren’t taped and secondly, the zip isn’t waterproof either. If you wanted and could be bothered, then the seams could be sealed with Silnet or similar and it wouldn’t be a mammoth task to attach a storm-flap over the zip. However, those who use a bivvy with additional shelter should find its weather resistance perfectly satisfactory without any modification.

Small enough and at 213g, light enough not to be a burden.

Dimensions are perhaps more adequate than they are spacious but that will largely depend on your individual circumstances, preferences and pie eating habits. Laid out flat, the width across the shoulders is 31″ / 79cm, the with at the toe end is 16″ /41cm. The overall length excluding the hood is 6′ / 185cm and including the hood, that increases to 7″ or 213cm. I appreciate that those figures may not mean much to you and what you really want to know is – can you get a mat, lofty bag and a body inside? Well, although still somewhat pie-dependent, I’m going to say yes but with the caveats that a tapered mat will fit much better, a long / wide mat will be a struggle and a ‘full-on’ winter bag may be pushing things slightly, so a potential reduction in loft may occur.

Both pack-size and weight are right on the money for an ultralight bivvy. As you can see up there ^, when packed, the thing’s not very much bigger than a 750ml water bottle and the weight is a very respectable 213g with stuff-sack. However, one thing it won’t do is compress very well, so bear in mind that once packed, you’re unlikely to crush it down any further … it behaves very much like Cuben fibre in that respect.

I think it ticks a considerable number of boxes for anyone in the market for a lightweight bivvy bag. Obviously, it’d be nice if the seams were taped and it had a midge net over the hood but I’m fairly sure the perfect bivvy bag has yet to be made. Obviously, there are compromises with every piece of kit and your requirements might not be the same as someone else’s. However, the edges of many a compromise can be smoothed once cost comes into play, which in this case is around £20. You couldn’t buy the materials to produce one for that much in the UK. Perhaps that’s the reason nobody does but it is the reason why I’ve reviewed it here.

Have a search for 3F Bivi at your favourite on-line Chinese market place.