Have a look on
www.briskoda.net I think that there is a
guide on some stuff and that question has been asked many times before - maybe use search on here too (if you have not already)! I'm at work but can answer that question tonight - I seem to remember that I bought a deep bi-hex Laser impact quality one (the easiest one to get with bi-hex as that nut is 12 pointed) - in fact the same Laser part number is quoted on one of these forums.
You could always "brass it" and phone up Star Performance if no one else replies!
Well I've looked on the Skoda site and it is a 36mm bi-hex socket - maybe deep socket, that you need to buy, as said already, you will probably find that the Laser Tools one is easiest to find.