The day will come when you may want longer wheel studs on your 928. Either because of a spacer set your using, or a thicker center plate on a new set of wheels, or because you race and the safety rules demand the studs protrude from the open steel nut.
These are a hardened, heat-treated direct-replacement wheel stud. Knock yours out and draw these in. Done!
The 66mm length is shown in the photos below where the wheel is mounted on the car.
The 100mm length is the best choice if you do not know what the combination of your wheels and/or wheel spacers might be. Just install them and trim to length as needed.
Sold in sets of 10.