SS 1 440 B C 7 Self-Seal Prefix Head Style 1 = Pan Head with Cruciform Recess Screw Size Diameter and Thread Specifica- tion 440 = 4-40 UNC-2A Length (1/16" Increments) 7 = 7/16 inch Screw Material C = CRES per ASTM A493, Type 302HQ O-Ring Material B = Buna-N (General ...