The M-4 mouse gets its power from the computer without a separate power supply as on the early models. The serial DB-25 plug is still available, as on the OEM mouse for Siemens, but the smaller DE-9 serial plug is becoming more common, as on the PC Mouse.
A reflective gridded mouse pad is required. Unlike the earlier Mouse Systems pads' coarse grid of about two dozen lines per inch, the M-4 uses a mesh several times finer of fine blue ink and infrared ink lines on a silver colored metal pad.
On the back label the MOUSE SYSTEMS brand appears in block italic font with the two triangular stylized mouses in outline and solid.
The labeling for the Siemens mouse— Siemens on the top. On the bottom:
Manufactured by MSC Techmologies, Inc. FREMONT, CA 94538 US Pat. 4364035, 4546347 Model M4 Mouse Systems (triangular mice logo) MSC 402098-001/51 S/N: MSC CY061891 SIEMENS TTL FCC ID: CWE7VT4
M-4 OEM Siemens optical mouse by Mouse Systems.
The labeling for the PC MOUSE— PC MOUSE on the top. On the bottom:
MOUSE SYSTEMS (Inside says REV. B) Made in Singapore for MSC Technologies, Inc., SANTA CLARA, CA 95051]US PAR .4364035,4546347 Model M4 901794-001/B SN MSC CL78223 US Patent 434035, 4546347
Mouse Systems continued to produce mice for other companies. The corporation made an OEM Model M-4 mouse for Quadram which had only two square buttons. The OEM M-4 mouse for Sun Microsystems used its modified RJ11 plug.