Metric Coarse

Metric Socket Countersunk Head Screws

Socket flat head in the USA are heat-treated to give a material strength grade of 12.9 for the USA market and 10.9 for the UK and European market, the exceptions in the UK and Europe are Unbrako and Holo-krome who are both 12.9. Due to the head geometry of the 12.9 Countersunk screws the service load in the application is only equivalent to strength grade 10.9.