The following information relates to the smaller Dk'tronics Mouse interface which is designed for the CPC464. The interface casing is designed to fit the case of the cpc464.
Looking at the pictures, the larger mouse interface appears to be made for the pcb has "Amstard CPC6128Mouse" written on it, but this is not confirmedwhile the smaller one appears to read "CPC464 Mouse".
Holding the PCB so that the mouse port is to the top-right, the following, which is not easy to see from the photos, is written on the PCB: