These are the wheel locks. The matching key socket should be in the front trunk in one of the holders that includes the tool kit and tow hook.

I don't think cars in the US market come with locks anymore, not sure about ROW. The last generation of Porsches (987/997) used to come with them from the factory.

 

I got a bill for service last month.

 

Here is Australia they don't come with them either. These were a gift from the dealer. He showed me where they stashed the socket in the tool kit when they fitted them.

I wouldn't feel too bad. I probably paid about 100k more than you did for the car. 100k buys a lot of swag...

 

Do you know if the wheel lock studs are GT4 specific or generic Cayman?