Parker Aerometric Full Sized Lustroloy (stainless steel) cap with chrome plated clip.  These caps had a matte finish with a thin shiny cap band when new.  Finish was more "brushed" than the earlier vacumatic series caps.  The finish did not stand up to wear too well and quickly wore off.  Available in both full and demi sizes.  Common Cap

Parker Aerometric Full sized and Demi sized Lustroloy (stainless steel) caps with gold filled clips.  These caps had a matte finish with a thin shiny cap band when new.  Finish was more less "brushed" than the earlier vacumatic series caps.  The finish did not stand up to wear too well and quickly wore off.  Available in both full and demi sizes.  Common Caps

Gold Filled Cap with 14k solid gold clip. Pattern is of horizontal and vertical lines forming "windows".  Sold as the "Heritage" model.  This is the aerometric series version, where the "Parker" imprint is superimposed over the lines pattern, unlike the earlier "window panes" were Parker was on a "cap band" by itself.  From the catalogs I have seen, it would appear that this was a very short lived model for 1948-1949.  There was also a version made in the demi size, which is even harder to find.  Uncommon Caps

Solid Gold 14k caps with 4 circles going around the cap and 14k clips.  This was the solid gold pattern introduced for the plain arrow clip in 1947 for the vacumatic "51" and carried over into the aerometric series.  Model was sold as "Heirloom" by Parker.  Note the "clicker" pencil, in contrast to the "rotary" pencil in the vacumatic series.    Available in both full and demi size. Rare Caps