Self Tapping Screw
Flat Undercut Phillips B-Type 18 8 Stainless Steel ANSI # 4x1/2
Major Diameter ANSI #4: 0.114" (2.90mm)
Total Length: 1/2" (12.70mm)

Manufactured to ANSI Standard (American National Standard Institute)
Screw Spec - ANSI B18.6.4 - Self Tapping Screw - Head Dimension (Flat Undercut)
Screw Spec - ANSI B18.6.4 - Self Tapping Screw - Head Type and Hole Size
Screw Spec - ANSI B18.6.4 - Self Tapping Screw - Thread and Material (Type B)