Metallics JG8HC72 Bolts 1/4-20 x 2-1/4 G8 HXBT St-zn (Jar 100)

It's a 1/4-20 coarse thread cap screw, 20 threads per inch, with a measured shank diameter of 0.2450 to 0.2500 inch. Any standard 1/4-20 nut or tapped 1/4-20 hole will take it. For a Grade 8 bolt, pair it with a matching high strength nut so the nut is not the weak link.

Grade 8 here means 150,000 psi minimum tensile and 130,000 psi minimum yield, hardened to Rockwell C33-39. Grade 5 in the same diameter is rated lower, which is exactly why automotive and fleet shops step up to Grade 8 on suspension, drivetrain, and high-load brackets. Where joint load is modest and you just need a fastener, Grade 5 is usually enough and easier on the tap.

The hex head measures 0.428 to 0.438 inch across the flats, which is the standard 7/16 inch wrench or socket size for a 1/4-20 hex cap screw.

The finish is zinc over medium carbon steel. Zinc plating handles indoor, shop, and sheltered outdoor service and resists general corrosion, but it is a sacrificial coating, not stainless. On continuously wet, coastal, or chemically exposed installs it will eventually rust through, so plan on a hot dip galvanized or stainless fastener there instead.

They ship in a jar of 100, and 100 count is the order minimum, so a jar is the smallest unit. Metallics notes other sizes and quantities are available by request.

The record flags it as ARRA compliant and Buy American compliant, with country of origin listed as China. If your contract language requires domestic melt and manufacture rather than the ARRA compliance flag, verify against your specific clause before submitting it.

Material standard is AISI 1021 to 1045 medium carbon steel, heat treated to Rockwell C33-39. Medium carbon heat treated fasteners should not be welded; the heat destroys the temper that gives you the 150,000 psi tensile rating. Use them as bolted fasteners only.