Metallics JG5HC58 Bolts 3/8-16 X 5/8 G5 Hxbt St-zn (Jar 100)

They are 3/8-16 by 5/8 inch hex cap screws. The 16 threads per inch is standard coarse (UNC) for 3/8 inch diameter, and the shank measures 0.3690 to 0.3750 inch outside diameter, so they thread into any standard 3/8-16 tapped hole or take a standard 3/8-16 nut.

Yes. These are medium carbon steel, heat treated to Rockwell C25-34, with 120,000 psi minimum tensile and 92,000 psi minimum yield. That is the normal spec for motor mounting, machinery bolting, and automotive or truck repair work. If your drawing calls out Grade 8 or a 150,000 psi tensile bolt, this is not a substitute.

The hex head measures 0.551 to 0.562 inch across the flats, which is a 9/16 inch wrench or socket. Head height is 15/64 inch, so clearance above the joint is minimal if you are working in a tight pocket.

The finish is zinc, a zinc chromate plating, which handles indoor industrial and lightly damp conditions. It is not stainless and not hot dip galvanized, so for direct weather exposure, wash down areas, or coastal sites, step up to a stainless or hot dip galvanized bolt instead.

JG5HC58 ships as a jar of 100 pieces, and 100 count is the order minimum, so it is sold by the full jar rather than loose. The jar weighs 1452 g. Metallics also offers other sizes and quantities on request in the same Grade 5 hex bolt line if you need a different pack.

The bolts are made to ASME B18.2.1-2012 for hex bolt dimensions and to AISI 1008-1026 material, so they drop into submittals that call out that dimensional standard. They are flagged ARRA compliant and Buy American compliant in the product record, with country of origin China, which is worth checking against your project's domestic sourcing language.

Grade 5 heads carry three radial lines; Grade 2 heads are unmarked. These are Grade 5, zinc plated steel, 3/8-16 by 5/8 inch, so once they are mixed in with plain unmarked hardware the three lines on the hex face are the fastest way to sort them back out.