That's because the Trackman is essentially the exact same mouse. Logitech's Trackman mouse is one in their line of cordless devices. It is an oblongish black mouse that sits ergonomically in your hand. It has a small trackball and three buttons on the top. All buttons and the trackball are supposed to be controlled by your thumb.
Installation is simple.
You just plug the receiver unit into your serial port and boot up your computer. The three mouse buttons are programmable using Logitech's Mouse Software. Programming is simple and you can program the buttons to do a variety of tasks, such as single click, double click, click-lock, etc. The mouse feels good in the hand and is easy to use. The Trackman is aimed at people doing live presentations in front of a large audience.