Metallics JMTLN6SS Nut M6 Hex Kep Lock Nut 18-8 SS (Jar 100)

These are M6 metric hex kep nuts, so they thread onto M6 bolts and studs. Metric only, so they will not fit a 1/4-20 or any other inch-series thread. Ordering code is JMTLN6SS.

The JMTLN6SS nut is 18-8 stainless steel, the austenitic 300-series grade used where plated carbon steel would rust. That makes it suitable for exterior and damp-location electrical work, enclosures, strut and equipment mounting. For salt spray or coastal exposure, 316 stainless is the step up from 18-8.

A kep nut (also called a K-lock or keps nut) has a free-spinning external star washer captured under the hex, so the washer bites into the mating surface as you tighten. No separate washer is needed, which cuts your parts count and keeps one hand free during overhead work. It is a one-time-use style fastener, best in jobs where you tighten and leave it rather than repeatedly removing it.

Each jar holds 100 nuts, and the jar is the pack type, so you are buying bulk count rather than individual pieces. That quantity suits a service van or a panel shop bin where M6 hardware gets consumed steadily.

Use the kep nut where the joint is metal-to-metal and you want the serrated washer to dig in and resist loosening from vibration, and where the assembly may see heat that would soften a polymer insert. A nylon insert nut is the better pick if the fastener has to come off and go back on, since the kep nut's star washer loses its bite after the first tightening. The JMTLN6SS covers the M6 metric size in 18-8 stainless.

Stainless on stainless can gall, and 18-8 is prone to it when run down fast with a driver. Thread these on slowly, or use an anti-seize on the stud, especially on longer threaded rod. Mixing with a plated carbon steel bolt avoids galling but gives up the corrosion match in wet locations.