An older Fidenza 2205, this color glass was used inthe 1920s and 1930s, in fact the date of 1930 is embossed on the edge of the top section. Newer insulators like the CA2205A (wider top able groove to accomodate aluminum wire) are aqua or clear in color. The light purple Fidenzas were manufactured in the 1960s. The 6205 (or CA 6205) has a heavier top section, but is otherwise about the same size as a CD 320 Pyrex. There is also a 1205, which is a one-piece insulator, as well as a 1205 CA, which is very similar to a Pyrex CD 320, the top saddle groove area is a little different. The one I have is a light green-yellow (or perhaps citrine) color, with very weak embossing on the top. This may be a CD 380, according to GIFONA.