Hey buddy, can you grab me a 15mm wrench? Forty-five seconds after asking your friend that question, you're wondering what's taking him so long. He returns to the engine bay shaking his head and ...

Hex wrenches, also known as Allen keys, are the tools you use to screw and unscrew fasteners that have a hexagonal recess (as opposed to a Phillips or flathead recess). Hex screws are commonly used on ...