An Allen wrench, AKA an Allen key or hex key, is a small hand tool used to fasten screws or bolts with a hexagonal socket. Either end usually works, although some sets only have one end.

Also known as hex keys, Allen wrenches are vital to any ... chances are the manufacturers included one or two of these handy ...

Bicycle-specific tool giant, Park Tool sends us their Sliding Hex Wrenches with some great features for review, and they are ...