Self Drilling Screws Hex Head Self Tapper Tapping Screw Metal Stainless Steel. Material: 410 Stainless Steel. 410stainless steel, It has high hardness, toughness and good corrosion resistance; Thermal strength and cold deformation performance, shock absorption is also very good. Thread diameter: M4.2 /M4.8 /M5.2 /M6.3. Measure the length of the screw, excluding the screw head. All bolts are fully threaded. According to your choice.