... and BS2470. grade 10.9/CSK head Specifications of DIN7991 flat head countersunk socket cap screw :Other names: countersunk flat head screws ; flat head machine screw ; flat ... , DIN913,DIN914,DIN915,DIN916set screw, DIN7991 hex socket flat head screw , ISO7380buttom head, DIN933 DIN931hex bolt, ISO7379 Shoulder screw,and Din6921 hex flange bolt). *Best ...