"Hearst Magazines and Yahoo may earn commission or revenue on some items through these links." Hex wrenches, also known as Allen keys, are the tools you use to screw and unscrew fasteners that have a ...

Ever wondered why there isn't an Allen key (or hex key, if you prefer) equivalent to the adjustable wrench or spanner? Turns out it's actually quite a complex engineering challenge. But this is 2025, ...