Square Recess Flat Head Fully Threaded Self Drilling Screw 18-8 Stainless Steel

Type BSD: The 18-8 stainless drill screw offers superior corrosion resistance while the 410 stainless screw will drill through harder material than the 18-8. The hardness of the material to be drilled should be a minimum of 10-20 Rockwell hardness points less than the screw’s hardness