Every well prepared rider carries a few things on each ride to make sure that in case of mechanical issues, they make it home!    One these indispensable items is a good multi-tool, the bicycling equivalent of a Swiss Army knife. One of the best on the market is the Topeak AliEN II.   The AliEN has been around for many years in the same basic format.   The reason it has changed so little over the last 20 years is because it just worked so well from the beginning.     It is very well engineered and the quality of the tools is the highest I've seen on any bicycle multi-tool.    It has almost everything you could ever need on the road to perform a repair, and the individual tools are so well made that I often reach for it even when I'm next to my well-stocked workbench.   I've had my current one for over 10 years and it's still going strong! It separates into two halves, to make it easier to fit into tight spots, or if you need to use more than one tool at a time.    One half has 8 Allen wrenches, Phillips and Torx T25 screwdrivers,  the other, 3 sizes of open end wrenches, spoke adjusting wrenches, a flat blade screwdriver, chain tool (great for fixing a snapped chain on the road!), knife and even a bottle opener for that well deserved end-of-ride beverage!  In addition, there's a separate clip-on part that has 3 box end wrenches, and a 15MM wrench  for pedals and internally geared hub nuts.  This clip on attaches to one half of the separated tool for extra leverage.   And if all that wasn't enough, each half has a molded in tire lever, for removing tires to fix flats! Recent updates include the addition of the Torx T25 screwdriver, the standard for disc brakes, and the chain tool will now handle the latest 10 speed chains. It's often said that “it's the little things that count”.    One example of the attention to detail the engineers paid when designing this tool was the fact that they used different fasteners on each side for the pivot bolt for all of the individual tools.  Why is this significant?  It means that you can use your AliEN to fix itself!   This level of thoughtful design is exhibited in the entire tool. Highly recommended!