seeking small trackball device that mounts to side of laptop

• Help me find a tiny trackball for use with a laptop. Key requirement: hangs off side of laptop, does NOT use desk space. My elderly father is on extended travel and is using his laptop for email etc. The laptop has a built in touchpad but he is wreaking all sorts of havoc with it. Normally he would use an external (USB) mouse to solve this but he left his at home, and anyway he insists that he does not have desktop surface to rest it on. He has a desk but there is only space for the laptop itself (long story). I know some laptops (maybe just IBM/Lenovo) have that tiny joystick in the middle of the keyboard but that probably wouldn't work for him either, and anyway his laptop doesn't have one. He does have a nice Logitech TrackMan trackball device at home (as do I) and he does very well with it, so I think he would be quite comfortable with a trackball solution for his laptop. I recall, many years ago, seeing a little trackball device that CLIPPED onto the side of the laptop. It either plugged into a side USB port, or just clipped on the edge somehow and then you plugged in a short USB cable. It tilted up at an angle and you then used your thumb on the ball and index finger on the button(s) to do your thing. Googling fails me, as does searching the websites of the major pointing dev mfgs, so apparently this device isn't sold anymore. But I just can't believe that. Has anyone seen a product like this, or have other recommendations?

• Answer:

  The trackball I have is the "http://imgur.com/a/pexRN", with the PS2 connection. The clips measure about 8mm, which is too small for my laptop, but presumably fit on some types.