GRK PHE9112HP R4 SS HandyPak 9 by 1-1/2-Inch Self-Countersinking Screws, 100 Screws per Package PHEINOX Stainless Steel with limited lifetime warranty Use GRK Bit T-25 Self-tapping countersink head W-cut thread design CEE thread design 2-Inch and longer with Zip-Tip