The M3Z differs from the M2U in that the M3Z a) employs a different
electronic design, b) controls active test points through the software (eliminating the toggle switch seen in the M2U), c) is expandable to 2560 test points, d) allows resistance measurement to be made, so you can check the quality of your connections as well as the value of embedded resistors, and e) allows measurement of diodes, complex networks, and backplane applications.
This photo shows catalog Item 826, the CableEye M3Z system with the CB15 board set attached. Remove the interchangeable CB boards by pressing apart the latches near the front of the board. Choose from over 60 different CB boards to accommodate over 200 standard connector types, and use the CB8 board for prototyping and circular connectors accomodating unlimited connector types. Like the M2U system, the M3Z control module offers a small bench footprint and the ability to handle cables and harnesses of up to 64 conductors plus accessories such as a footswitch, probe, or minihooks. For larger cables or harnesses, attach an expansion module to the bottom of the control module (Item 827) and vertically stack more until you achieve your desired test point capacity to a maximum of 2560 test points. See below for rear view and side view. USB interface standard. A computer is required even though one is not shown in this photo.