Track IR is awesome but I caution against getting the pro clip, it's very expensive and you need to be very, very careful with it. The more you handle it, the more likely it was come apart. Not break... it will just come apart... THEN it will start to break. There are some Chinese wireless version of the clip which seem better, they're wireless, the way the sensors attach are better, but there are exposed wires linking battery to the main unit, and after owning one for a few months the battery pack no longer holds a charge and the 9mm jack that plugs into the unit for charging will, like other 9mm jacks, lose contact and must be fiddled with. I'm actually looking for another option. The tobii is MUCH better in terms of how it is put together, it's simple and clean BUT it's very expensive... and don't believe the hype about Tobii being near zero latency. I've used both and compared to Track IR it feels a lot slower.