Crank Brothers Multi-10 Tool
This Crank Brothers multi-tool has a design that's simple and functional. All the tools you will need out on the trail and that fits perfect in any hydration pack.
About 70 miles into a 150-miler, I hit a pothole and my handlebars shifted to a resting position where they pointed at the ground. One of my riding friends had this in his bag and we quickly fixed my bike (and tightened up the seatpost while we are at it). Ever since, this tool has been in my saddlebag on every ride.
This is the perfect multi-tool. It's light, strong and compact. The only problem with this is it does not like water. There was a rain storm that got my pack wet and I forgot it was in there. Several days later when I got it out rust has started to set in. A minor inconvenience, as this doesn't affect the functionality in anyway but still not cool. Other than that I would give it a 5.