M12 hard washer

There are certain fasteners on a car which require use of a high quality hardened washer, and a regular washer simply is not good enough for the job.  These are often torque critical items such as main bearing caps, underneath cylinder head bolts or nuts.   

This washer is for an M12 fixing, so has an ID of just over 12mm, an OD of 19mm (3/4") and measures 3mm thick. 

Used on Fulvia 1600 and also Aprilia engines.