3 is very useful and unless you are doing something very specific this will work. They use 3 USB ports (small USB dongles that connect to the trackers wirelessly). You need at least a 1.0 or 2.0 beacon base station, but I use 2 1.0 base stations with a 3.55mm cable to sync them up and it works really well. I also use them with an Oculus CV1 and use a Steam VR app called Space Calculator to sync them (see YouTube video). They can last around 5 hours or more, at least 4 hours, on a good day almost 6 hours. It takes about an hour to charge, sometimes longer.
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