I needed a 4 mm hex key with the longest possible arm length to apply some serious torque on four 4 mm hex bolts in an end cap on the handlebar of my high-end electric bicycle. Look around and the you'll see that the longest 4 mm hex key (the arm length) you can find is 140 mm. Only KC Tools had a 4 mm hex key that exceeded 140 mm: this Gedore 4 mm hex key with an arm at 6-3/8 inch or about 161 mm. What I didn't like about the tool is Gedore provides virtually no information on the arm length and manufacture of their tool, including the hardness of the steel and the finish, etc., as Wera does. Consequently, it gets a 4-star rating. I bought it anyway, and I did use it to perform the final cinch down on the end-cap piece that holds the handlebar in fixed position, and baby, it's in tight, real tight. I was able to get far more torque on those 4 mm hex bolts with this key than I could with any of the American hex keys I've used previously, and I did not experience tool slippage or chamferring of the hex bolts. I would rate this tool second to Wera in quality--at least Wera provides far more information on the manufacturing quality of their tool. But when you need to apply some serious torque on a small hex bolt, this is your tool of choice.

For working on highend bicycles, this tool is always in my hand. It is solidly built and has a great feel in your hand.