Metallics TRS8-6BLK Thread Rod 3/8-16 x 6' Blk-Ox (Piece 1)

That's exactly what this rod is for. 3/8-16 is the common trade size for hanging electrical conduit, channel/strut, cable tray, and light fixture supports, and the 6 foot stick cuts down to whatever drop you need. It's carried as an electrical-division item, so it pairs with the 3/8 hanger rod nuts, spring nuts, and rod couplings you'd already be using on a strut run.

Keep it inside. Black oxide is a thin conversion coating with very little corrosion resistance on its own, so this rod suits dry interior work, above ceilings, and mechanical rooms. For exterior, wet, or corrosive locations, specify electro-galvanized, hot-dip galvanized, or stainless 3/8-16 rod instead.

The TRS8-6BLK is the rod only, 3/8-16 x 6 feet. Nuts, washers, rod couplings, beam clamps, strut spring nuts, and any anchors into the deck are separate line items. Match everything to 3/8-16 so the threads engage properly.

It's catalogued as a bundle pack, so the 6 foot 3/8-16 black oxide rod comes bundled rather than as a loose single stick. If you're buying for a job that needs a known count of drops, work out your total linear footage first, since a 6 foot stick yields several hanger drops once cut.

Yes. Because the rod is fully threaded 3/8-16 along its length, two 6 foot sticks join with a standard 3/8-16 rod coupling (hex coupling nut) to make a longer drop, and cut ends can be cleaned up with a 3/8-16 die so the nut runs on freely.