Model Numbers: Keuffel & Esser slide rule model numbers often have alphabetic prefixes and suffixes.  For example "N4081-3" indicates a "new" revsionof already existing model 4081-3.  These revisions usually amounted to nothing more than a re-arrangement of the scales; the physical sizesof models with and without the "N" are absolutely identical.  Any case or cursor that fits a model without the "N" will also fit the model with the "N."  The "N" was usually dropped after couple of years when people had gotten used to the new scale arrangement.
    The suffix indicated what kind of case the rule came in.  4081-3S (and N4081-3S) came in a sewn leather case.  4081-3F came in an imitationleather fiber case.  So, ignore the alphabetic prefixes and suffixes when looking for parts for you slide rule.  If yourrule is marked "N4093-3F," just look for model 4093-3.
    The -1 or -3 or -5 in the model number does make a difference.  "-1" indicated a "five-inch" rule; "-3" a ten-inch rule and "-5" a 20-incher.  Twenty-inch rules usually--but not always--use slightly different cursors from the corresponding ten-inch versions.

Quantities are limited (sometimes only one).  USED ITEMS HAVE BEEN CLEANED AND RECONDITIONED.  If what you need is not available check back later; maybe we'll find one somewhere.  Email us if you need something not on this list or if you're not sure what you need.

Note:If the OEM glass lens or cursor blocks are shown as "N.A." (not available), we have Replica Laser cut acrylic lens and 3-D Cursor Blocks on the Restoration page.
$5 blanks or $10 if I add the hairline on the lens or tap the 1/72-UNF threads on the blocks.