Diameter: 3/8"
Length: 4-1/2"
Material: Steel
Finish: Yellow Zinc
Head Style: Hex (9/16" Wrench)
Thread Size: 24 (Fine)
Thread Length: 1"
Hardness: Grade 8
Type: Cap Screw

Box of 25.

A hex cap screw has a hexagonal head, designed to be driven by a wrench.