These head studs are a new addition to the ARP line up. These 10mm head studs are spefically made for a 06a blocks in all 99.5+ 1.8t mk4 engines, AWD, AWW, AWP etc as well as 2001+ audis with internal waterpump engines. These are a much better choice than raceware head studs for several reasons. Higher clamping load, better materials, allen key depressions broached into the end of the stud for easy removal and installation of the stud. This is very important because 99% of 1.8t transverse motors cannot remove the head with manifolds on while using head studs. You will hit the rain tray forcing you to remove you entire turbo kit. With these studs you can unscrew the hardware with an allen key and take the head off just as easily as you can with stock head bolts! We recommend using these studs on any project making in excess of 600whp. We have made over 700whp on stock head bolts without failure but do not recommend it for extended use. All ARP hardware is reusable unlike the factory hardware.