This ZF39 type scope was made by K. Kahles in Wien. These 4×60 sniper scopes were given the code “cad” during WWII. They were used on SSR, LSR and high turret mounts (like this one).
Sniper Scopes
Sniper scopes from WWI to WW II
Sniper Scopes 
Very nice addition to collection Laurent
Thank you Dave but this one is not mine, unfortunately 🙂