Jaegers 6" f/10 "GJD" OTA Construction - Flint Element (Edge View 2)
 

The flint element for the Jaegers 6" f/10 GJD Refractor - Side 2 (Click to see an enlarged image.)

 
The other side reveals another set of numbers along with what appears to be an alignment mark. The number "60", which I believe is the focal length and a set of numbers (5-85), that I am not familiar with.