Packaged Items
SinglePack of 5
MaterialThreadPart Number
Cad Plated9/16-18AN365-918


These precision-made nuts are reliable and economical fastening devices The fiber insert gives a friction grip on the threads of the bolt and holds securely. The AN364 (thin) stop nut is for use in structural applications where the bolt is loaded primarily in shear or in any application where the tensile strength of the regular height AN365 is not required. Cad stop nuts are furnished to military specifications. Stainless is furnished to military specification and commercial grade.

AN364 (supersedes MS21083) - cad plated stop nuts
AN365 (supersedes MS21044) - cad plated stop nuts
California Prop 65 Warning Symbol

WARNING: Cancer and Reproductive Harm -

Reference Chart


This nut is absolutely fabulous. Not as good as an almond, but great. It has tiny little grooves on the inside. If you twist it onto a piece of metal that is long and skinny with matching grooves it is almost like they are glued together - except you can change your mind and un glue them by twisting the other way. Ill buy more.

Walter S Verified Purchase


October 26, 2021

I intend to use these in a Live Steam hobby project. I intend to use them to join one inch high Steel rail sections together.

William S
April 20, 2021

Always a pleasure to see the folks in West Chicago. They are so helpful and greet everyone with a smile. Thank you for coming to the Midwest. I look forward to the time when you start carrying wood, as I am restoring a 1942 Stinson L-5 Sentinel and a 1945 Percival Proctor - both ground up restorations. Thanks for your assistance.

Bob C
February 18, 2021

They lock! True AN hardware to Mil Spec.

Jose G
February 5, 2021

Exact size ordered, work perfectly.

Robert M
February 4, 2021

These things are the way to go for very secure connections

Art B
January 27, 2021

I write reviews as a hobby. However, its kind of hard to attach a Product Review to a lock-nut. Nevertheless, AircraftSpruce requested my assessment. These appear to be very well-made. While I do not know the country origin of manufacture, Im hoping these are NOT made in China. I think it would be in the best interest of AircraftSpruce to list Made in America whenever it applies. On the admin side, AircraftSpruce efficiently managed my multiple orders. The real test will come over time, both functionally and weather or not AircraftSpruce carpet-bombs me with ads.

Daniel O
January 18, 2021

Excellent quality.

David M
December 12, 2020

Everything arrived ahead of time and in good shape

John D
November 30, 2020

Arrived undamaged

November 23, 2020


Please note, Aircraft Spruce's personnel are not certified aircraft mechanics and can only provide general support and ideas, which should not be relied upon or implemented in lieu of consulting an A&P or other qualified technician. Aircraft Spruce assumes no responsibility or liability for any issue or problem which may arise from any repair, modification or other work done from this knowledge base. Any product eligibility information provided here is based on general application guides and we recommend always referring to your specific aircraft parts manual, the parts manufacturer or consulting with a qualified mechanic.

Q: What is the color of the plastic in the AN365 elastic stop nuts?

For the certified version, the plastic will be either green, red, yellow, or purple. The different colors denote the different approved manufacturers. For the commercial grade stop nuts, which have not been tested to the MIL spec, the plastic will be white.

Q: What is the thickness of the AN365-624? This is for bolt length planning for propeller installation.

AN365-624A thickness/height is .453".

Q: AN365-1032 ELASTIC STOP NUT: What is the height/thickness?

The data sheet I have has the height at .236" +/-.016", and thickness/flat surface across flat surface, is .375".

Q: Is this the same nut as a MS20365-720C?

MS20365-720C is a 7/16-20 all metal stop nut. We offer AN363-720 and NAS1291X7 that are all metal, 7/16-20 all metal stop nuts. Either should work for an MS20365-720C unit.

Q: What is the replacement of the MS21044N8?

AN365-820A is MS21044N8.

Q: I would like to know the difference between: AN365C-1032 and AN365-1032C

These are both the same as the "C" represents that they are stainless steel.

Q: What is the replacement of the MS21044N04?


Q: What is the difference between a AN365-428C and an AN365-428A?

The C designates stainless steel. The A will be cad plated steel.

Q: What does it mean when you dont have the letter A at the end -AN365-xxxA -?

The A nuts will be cad plated steel.

Q: What is the reference of the elastic stop nut for AN5 and the reference of Washers for AN5?

AN5 bolts use AN365-524 locknuts and AN960516 flat washers.

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