The link is just for the socket with a plastic sleave to protect your alloy wheels.
The locking nut 'keys' are diffrent from car to car, you need to check all the cubby holes in the car for the key,or get a new one from the 'stealers'.
I think it's 19mm,if stuck I can nip up to my garage,but it's , halfords also sell them for a similar price.