Metallics SFN1420SSB Nuts 1/4-20 Serr Flange Locknut SS (Box 1000)

It's a 1/4-20 nut, so 1/4 inch diameter at 20 threads per inch (UNC coarse). It mates with any standard 1/4-20 bolt, screw, or threaded rod.

No. The flange acts as the bearing surface, with an outside diameter of 0.574 to 0.594 inches, and the serrations under it bite the work surface to resist loosening. That's the point of the design: one part instead of nut plus lock washer plus flat washer. On soft or finished surfaces the serrations will mar the face, so use a flat nut and washer there instead.

They're 18-8 stainless steel, which is the standard austenitic grade used for general corrosion resistance outdoors, in wash-down areas and damp plant rooms. Pair them with stainless bolts of the same grade; mixing stainless nuts onto plain or zinc-plated steel bolts in a wet location sets up galvanic corrosion on the plated part.

Across the flats the hex measures 0.428 to 0.438 inches, which a 7/16 inch socket or wrench takes. Overall across the flange it runs 0.488 to 0.505 inches and the nut stands 0.222 to 0.236 inches tall, so allow clearance if you're working in a tight channel or strut.

They're built to ASME B18.16.4-2008, the dimensional standard for prevailing-torque and free-spinning lock nuts. That matters on a submittal where the spec calls out an ASME dimensional standard rather than a brand.

The SFN1420SSB is flagged both ARRA compliant and Buy American compliant, so it clears those procurement requirements on public work. Country of origin is listed as multiple, so if your contract requires a single named origin on the submittal, state that up front with the order.

They ship as a box of 1,000 and that quantity is the order minimum, so it's a full-box item rather than a counter pack. Other sizes and quantities can be arranged by request. The packed box weighs 8.95 lbs.

Treat it as single-use on the locking function. A serrated flange nut locks by the teeth embedding into the mating surface, not by a nylon insert or deformed thread. Once those serrations have cut into the panel and you back the nut off, both the teeth and the scored surface are worn, so the resistance to vibration loosening drops. Install a fresh nut on reassembly.

The rated panel thickness is 0.04 inch. Below that the serrations can dish or tear thin gauge sheet rather than bite it, so back it up with a washer or a thicker bracket on light material.