Thread Diameter 8 mm Head Diameter 16.00 mm Head Height 4.40 mm Allen Hex Drive Size 5.00 mm These Flat Head Socket Cap Screws have a 90 degree countersink and are made of A2-70 stainless, which is a grade 304 stainless steel with a 700 N/mm2 tensile strength. The -70 represents the tensile strength divided by 10. Flat Head Socket Cap Screws length is measured in their entirety, which is from the top of the head to the tip. A flat head is cone shaped for use in countersunk holes and has a flat top that fits flush with the mated surface. Stainless steel socket cap screw has a plain finish and a flat head with an internal hex drive. Stainless steel resists corrosion and may be magnetic. The flat head is cone shaped for use in countersunk holes and has a flat top that fits flush with the mated surface. The internal hex drive, also known as a hex-socket drive, has a hexagonal slot that requires an Allen key driver, also known as a hex key or Allen wrench.