In 1995 Mouse Systems, owned by KYE since 1990, produced the world's first mouse with a scroll wheel. It sold as Mouse Systems ProAgio and Genius EasyScroll under Kye. With the wheel in between the two front buttons you could surf the Net without using the scroll bar, for $49.99. Apparently it wasn't marketed aggressively so it made no waves. Microsoft seized the idea and marketed the concept as part of their IntelliMouse® in 1996.
The first scroll mouse for the PC boasts five buttons and the ProAgio model wears the Mouse Systems double mouse logo on its top. It connects to the PC with a PS/2 plug.
The five buttons and the ribbed edges fit pleasantly in the hand with tactile bumps on the left button and a scroll wheel in the middle on top, much wider than later iterations. The reference to Combo in its name must be the scroll wheel which responds to pressing as a button as well as scrolling up or down by rolling it. The thumb operates a thin strip button on the side. Presumably, you can designate the buttons' functions with the software.
The mouse uses optical mechanical technology at 400 DPI, with its ball tracking exactly in the middle.
Label on bottom:
MOUSE SYSTEMS [logo] Scroll Mouse (Combo) Mouse Systems Corporation 4705 Seabridge Drive Fremont, CA 94538 MSC P/N: 404252-001 FCC ID: FSUGMZFA MADE IN TAIWAN This device complies with Part 15 of the FCC Rules. S/N: 97000565 K3007950