1. square, rectangular, hex and dome heads 2. dimensions from 5/ 8 inch thru 1-1/ 8 inch 3. medium carbon steel not heat treated or medium carbon steel heat treated to A-325 specifications. 4. spring washers and screw inserts are available . 5. other specifications available based on your drawings. 6.Applied on railway lines equipment with wooden sleeper , turn-outs, and switches.