<aside>

SteamVR Headsets like the Valve Index, have two internal dongles built in. These can be used to pair the headset to two Index Controllers, or two 3.0 Vive trackers.

If you're already using it to connect to two Index controllers, then you can’t pair any additional devices (like Vive or Tundra trackers) to those same dongles.

This is where external USB dongles come in.

</aside>