MS21042 Style B Jetnut, All Metal Locknut, SAE UNF Threads

MS21042 Jetnuts (Kaynuts) are all-metal, self-locking nuts manufactured to military specifications. They are rated at 160,000 psi tensile strength and can withstand temperatures to 450°F. Because of their reduced hex dimension, they are widely used in limited space applications where wrench access is a problem.

Jetnuts are also lighter than AN365 Nylon Lock Nuts (an average of 63% lighter for -3 through -6 sizes). Replacing all of the AN365 nuts on your racecar with MS21042 jetnuts can result in a measurable weight savings!

These are the latest "Style B" specification, with a slightly thicker flange which reduces the likelihood of splitting due to nut dilation (especially if over-torqued). Plated steel construction; some lots have a moly lubricant coating over the plating at the manufacturer's discretion (sorry, no choice on our end). Plating color may vary from photo. SAE (fractional inch) UNF (fine) threads only. Sold individually.
 

* The hex is typically deformed to produce the self-locking action. An unused nut may appear to have one hex dimension smaller than the others before installation.

Looking for metric sizes? We also offer (non-milspec) Metric Jetnuts which have similar temperature and strength ratings.

Reusing Locking Nuts
The FAA has issued guidelines on the reuse of locking nuts. Specific recommendations have been published for larger sizes (7/16-20 and up), but the general rule is that you should not be able to turn the nut by hand once the locking portion engages the male threads. If you can turn the nut with your fingers, it must be replaced. When in doubt, replace!