The embossing of the first insulator (pictured on the left) is:

1099 / ISOREX // FCSF (Dimensions - 3.5" x 4.5")

The embossing of the second insulator (pictured on the right) is:

ISOREX / FCSF // 234 (Dimensions - 3.2" x 4.4")

[IFONA CD ???]