Hello Hans-Jürgen

Seems to be a clone of RS-1680L, but it has 64 levels with differents mode (fun, beginners, aggressive,pratical, fixed deep, brute force, passive and normal), and problem level (> 2 pawns).

See https://www.spacious-mind.com/html/portable_1750l.html
and https://www.manualslib.com/manual/13...ack-1750l.html

Cordially.