Lustraloy (stainless steel) caps with gold filled clips.  These caps had a matte finish with a shiny cap lip when new.  Finish was more "brushed" than the later aerometric series caps.  The finish did not stand up to wear too well and quickly wore off.  These caps are the most often found on the vacumatic "51s".

Sterling Silver caps with gold filled clips, lined pattern with chevron band.  These caps all had a rhodium plating to prevent tarnish.  The finish did not stand up to wear too well, wearing inconsistantly, leaving a very unattractive appearance.  In addition, the soft metal is very prone to dents and dings, and finding caps in perfect condition is very hard.  These caps are the most often advertised version of the vacumatic "51s" found in print ads.

Lustraloy (stainless steel) caps with "Jeweler's" band and gold filled clips.  These caps had a matte finish with a shiny raised cap band when new.  Finish was more "brushed" than the later aerometric series caps.  The finish did not stand up to wear too well and quickly wore off.  These caps were also available with nickel plated clips.

Lustraloy (stainless steel) caps with "Jeweler's" band and nickel plated clips.  These caps had a matte finish with a shiny raised cap band when new.  Finish was more "brushed" than the later aerometric series caps.  The finish did not stand up to wear too well and quickly wore off.  These caps were also available with gold filled clips.