This is the manual for the Turbo64 accelerator cartridge plus some addendums, pictures and the floppy disk that comes with the cartridge.  Here is a quote from the manuals introduction:

We congratulate you on your purchase of one of the best hardware add-ons available for Commodore C64. With Turbo 64 your Computer becomes one of the most efficient home computers in the world.

To develop the TURBO PROCESSOR it needed a lot of research and time as we wanted to develop a card which is simply plugged into the expansion port and runs. We also discovered that one C64 is not the same as another C64. There are many different versions with different timings, i.e. a C64 made in England is different from the one made in USA. Therefore you will find on the PCB of TURBO PROCESSOR three trim pots for adjusting the timing to suit your own C64.