Possibly the lightest, most packable 16-litre rucksack you can find, the Illusion Pack was designed to carry 60m of 10mm rope to the crag but it also doubles as a super-light climbing backpack. Can also be used as a rope bag when rappelling in high winds, feed the rope out as you go. Folds into its own pocket and weighs just 280g.
Read more at http://www.ukclimbing.com/gear/news.php?id=4108