At 23:49 20 February 2013, Matt Herron Jr. wrote:
On Wednesday, February 20, 2013 2:53:56 PM UTC-8, Nyal Williams wrote:
Less than 5 hours use. Interested parties call 765 289-6059

what is an IR tracker, and what is it used for?

You can search this on the web and see pictures. See Natural Point IR
Trackir

(Note spelling :Trackir)

It is a device used with internet gaming programs, such as the Condor
gliding simulator. Software and two reflector devices (one on the top of
your monitor and the other on a cap you wear reads slight head motions and
sweeps the display on the monitor. A very slight change results in much
larger sweeps such that you will get a ninety degree view to the side with
about a 10 degree turn of the head. It also works for up and down views.
This eliminates the need for a "hat" switch on the flight stick.

They are used in all sorts of gaming programs.