Diameter: 3/8"
Length: 1-1/4"
Material: Stainless Steel
Head Style: Hex (9/16" Wrench)
Thread Size: 24 (Fine)
Thread Length: Full
Hardness: 18-8
Type: Cap Screw

Box of 8.

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