What is a locking wheel nut key?

Sounds like a random combination of unconnected words, is actually quite an important device if you have alloy wheels.

If your car has alloy wheels, then you very likely have a set of locking wheel nuts installed. A special key is required in order to remove them, adding an extra layer of protection against theft.

It is important that you keep the key handy, as the mechanic will need it whenever you require a tyre change or a brake (or suspension) repair or replacement.