Petzl Micro Traxion
Very compact and light multi-purpose pulley-jammer. Weighing 85g and with side dimensions less than a bank card, the Micro Traxion functions as a pulley, a pulley jammer combination, and an improvised hand ascender.
The pulley is a sealed bearing, which makes it resistant to mud, grit, and ice; and makes it much more efficient than its size would imply. It rates as more efficient than the larger Mini Traxion, and a little less efficient than the Pro Traxion - a much bigger, heftier object intended for quite a different purpose.
The Micro Traxion seems most appropriate for occasional and emergency usage. It will work very well for expedition use, and for those cavers who have a responsibility for others on a regular basis, but who do not need the Pro Traxion. Its weight, versatility and efficiency make it deserve to gain a wide following among vertical cavers as well as Alpinists.