Metallics JSFN3816 Nuts 3/8-16 Serr Flange Locknut St-zn (Jar 100), 100 Pack

It is a 3/8-16 nut, 16 threads per inch, which is the standard coarse (UNC) pitch for a 3/8 inch bolt. So it runs onto ordinary 3/8-16 threaded rod, strut hardware, and hex bolts. It will not fit a 3/8-24 fine thread fastener.

Across the hex flats the nut measures 0.551 to 0.562 inch, so a 9/16 inch wrench or socket is the size to grab. Overall width across the flange runs 0.628 to 0.650 inch and the flange (washer) outside diameter is 0.728 to 0.750 inch, so leave about 3/4 inch of clearance around the hole. Wrenching height is 0.23 inch, with total nut height 0.330 to 0.347 inch.

No. The serrations on the underside of the flange bite into the mating surface as the nut is tightened, so the flange does the job of both a washer and a locking device. A separate flat or split washer under it actually defeats the serrations, since they need to bear on the workpiece itself. The flange also spreads bearing stress over a wider area than a plain nut.

Yes, the flange will span oversized or poorly aligned holes, which is the usual reason to reach for one on a field-drilled panel. Minimum panel thickness is listed at 0.04 inch, so it suits sheet metal enclosures and light gauge channel. Flange outside diameter is 0.728 to 0.750 inch, which is the real limit on how big a hole it will bridge.

No. It is not Buy American compliant and not ARRA compliant, with country of origin listed as multiple. If your project carries domestic sourcing requirements, this nut will not satisfy them and you need a domestically produced fastener instead.

Steel with a zinc finish. Zinc plating handles dry interior and normally damp conditions, which covers most mechanical rooms, enclosures, and ceiling work. For wet exterior or corrosive service, go to a stainless flange nut instead, since zinc plate is a sacrificial coating rather than a corrosion-proof base metal.

They come 100 to a jar, and the jar is the order minimum, so one unit is 100 nuts. Package weight is 1.9 lbs. The jar packaging keeps them from scattering in a gang box or on a service truck.

It is built to ASME B18.16.4-2008, the dimensional standard for hex flange lock nuts, and hardness is listed at Rockwell HR15N 78-90. Those two values are what a spec reviewer or institutional procurement group usually wants on the submittal for a fastener like this.

It will not gall screw threads. The locking action comes entirely from the serrated flange face bearing on the workpiece, not from a distorted or deformed thread, so the mating bolt or rod threads stay clean. That matters when you are reusing threaded rod or backing a nut off a conduit hanger.

The JSFN series runs other sizes and pack quantities beyond the 3/8-16 jar of 100, available by request. Specify the thread size and the quantity you need and it can be sourced from the same series, so the whole job stays on one fastener style.