NAS1291 low-height self-locking hex nuts.

// DIMENSION GUIDE

Nut thread, width across flats and height

Schematic only; not to scale. Letter labels are keys for this illustration. Use the applicable part specification for dimensions, tolerances and measurement conventions.

// PART IDENTIFICATION

Keep the locking construction in the callout

NAS1291 is a low-height, lightweight self-locking hex-nut family. The C3M and C4M parts shown here use all-metal construction in A286 with an approved dry-film lubricant. They are different selections from the MS21083 nonmetallic-insert family.

Check the thread, hex clearance, nut height, material and surface treatment against the drawing. Thread size alone does not establish an acceptable replacement.

// STOCKED SELECTION

Stocked NAS1291 part numbers

Stocked items are subject to prior sale. Request a quote to confirm current availability and lead time.

Thread and material entries support part identification. These selected records are not the full series, an acceptance drawing or a live inventory feed. Include the required specification issue and documentation with your inquiry.

// PART-NUMBER EXAMPLES

C3M and C4M identify different thread sizes

NAS1291C3M identifies the 10-32 selection; NAS1291C4M identifies 1/4-28. For these references, C identifies A286 and the M ending is associated with the dry-film-lubricated configuration.

Retain the complete suffix. A NAS1291C4 callout without M is a different configuration in the reviewed standard; it should not be quoted as interchangeable with NAS1291C4M.

// FAMILY COMPARISON

Compare nut families before proposing an alternate

These descriptions explain the distinction between families. A change in series, material, finish or locking mechanism requires review against the controlling requirements.

// REFERENCE SCOPE

Match the required standard issue

The selected C3M and C4M identifications were checked against NAS1291 revision 13, dated February 28, 2010. Use the issue required by your drawing and purchase order for full dimensions, qualification and acceptance. This selected-part reference does not establish the latest revision or a blanket replacement for other standards.

// SOURCE WITH WEBSON

Send the complete requirement to Webson

Include the full part number, quantity, delivery date and any manufacturer or certification requirements. Preserve lubrication and finish details in the inquiry so Webson can review the required configuration for quotation.