NaturalPoint TrackClip Pro
Even more accurate, thanks to TrackClip Pro.
The NaturalPoint TrackClip Pro is a light-weight addition to the TrackIR 4 and TrackIR 5, which can be simply installed on almost any headset. The active LEDs in the clip create extra accuracy and a greater range (compared to the Vector clip), to a maximum of 1.5 metres (5 feet). Connecting the TrackClip requires a free USB port.