Know your gear
Accommodates right and left-handed users by placing mice on both sides of a computer.
The Y-mouse Dual PS/2 Mouse Adapter Port works with all systems that support a PS/2 mouse. Both devices need to use similar mouse protocol. Trackballs, Touchpads and Mice are all relative coordinate devices that use similar mouse protocol.
Switching between devices helps avoid repetitive motion problems
Daisy chain to attach even more pointing devices at a time
The PS/2 Y-mouse also supports most scrolling mice.