5/16X1 Medium, Standard Duty Coil Pin Plain Steel And Oil ISP The head has a socket

The head has a socket in the center that allows it to be driven with a hex key or Allen wrench

They have a slotted indented hex washer head that provides a large bearing surface and helps to prevent the screw from stripping

Introducing our premium 7/8-9 x 9 Hex Tap Bolt

while the split lock and narrow flat washer help to prevent the screw from loosening

The screw has a serrated hex flanged washer head that provides a secure and vibration-resistant connection

5/16X1 Medium, Standard Duty Coil Pin Plain Steel And Oil ISP The head has a socket5 16" x 1" Medium, Standard Duty Coil Pin, Plain Steel and Oil: Material: Plain steel Finish: Oil Diameter: 5 16" Length: 1" Type: Medium, standard duty Application: Used to secure two or more parts together, typically in applications where high strength and durability are required.