Metallics JG8HC21 Bolts 5/8-11 X 1 G8 Hxbt St-zn (Jar 25)

It's a 5/8-11 bolt, 1 inch long. Coarse thread at 11 threads per inch, with a shank outside diameter of 0.6170 to 0.6250 inch. So it mates with standard 5/8-11 UNC nuts and tapped holes, not fine thread.

Yes, the JG8HC21 is flagged both Buy American compliant and ARRA compliant. Country of origin is listed as multiple, so if your contract requires a specific origin on the mill certificate, that's the detail to pin down rather than the compliance flag.

Zinc finish over a steel body gives you ordinary corrosion resistance, fine for dry interior, enclosed, and sheltered equipment mounting. For sustained weather exposure, washdown, or coastal work, zinc plating is not a long-term coating; hot-dip galvanized or stainless is the route there. Note that galvanizing and Grade 8 are generally not combined, so a wet-exposure job usually means stepping to a different fastener spec.

The JG8HC21 ships in a jar of 25 bolts. The order minimum is 50 each, so a single jar won't clear it, plan on two jars per line. The jar as packed weighs 3407 g.

At 1 inch overall length under the head on a 5/8 diameter bolt, expect it to be threaded essentially full length, which is normal for short cap screws. Budget your stack carefully: material thickness plus washers plus nut height has to live inside that 1 inch. If you need more grip, the same G8HC and JG8HC series runs other lengths.

Match the nut to the bolt. A 150,000 psi minimum tensile Grade 8 bolt wants a grade 8 (ASTM A563 Grade DH or SAE Grade 8) nut, otherwise the nut threads strip before the bolt ever reaches its rated load and you lose the reason you bought Grade 8. Thread is 5/8-11 coarse, and hardened washers are the usual companion.

Material standard is AISI 1021 to 1045, a medium carbon steel, quenched and tempered to the Grade 8 hardness range of Rockwell C33-39. That heat treatment is what carries the strength, which also means these shouldn't be welded or re-heated after the fact.