This is an OEM zinc-plated intake stud with a special thin-walled 11mm nut (makes getting a wrench/socket on the nut much easier in confined spaces).
Fits cylinder heads found on the M10/M20/M30 engines.
Please note that the M20 has three longer studs on the intake side of the head (2 for thermostat housing and 1 in the middle of the intake manifold). Please select the option above for the three M8 x 70mm long studs with three brass nuts. OEM reference #07129908142