This is the manual for a programming aid called "HELP 128 Plus C 64" by Print Technik.  The following is from the manual:

HELP 128 PLUS C 64 is a modul to make programming and checking of own programs easier. It will be delivered as a Cartridge-modul. This modul must be inserted in the CARTRIDGE EXPANSIONS SLOT after you have switched off the Commodore. After inserting and turning on again the Computer you will see on the monitor the normaly SWITCH ON picture and the statement PRINT-TECHNIK HELP 128 PLUS 64, or " * PRINT-TECHNIK HELP C64 PLUS * "