Vive Ultimate Trackers now work on PC, though this support is currently in beta.
What Are Vive Ultimate Trackers?
Previous Vive Trackers used Valve's SteamVR Tracking system and thus required SteamVR Tracking base stations. Vive Ultimate Trackers, released in November, have two wide field of view cameras and an onboard chipset instead to perform inside-out positional tracking of the same kind most headsets now use to track themselves. They don't need base stations nor to be within view of a headset’s cameras, can directly work with standalone headsets.
It's approximately 50% smaller than Vive Tracker 3.0, though it's 25% heavier at 94 grams. HTC claims up to 7 hours of battery life, very close to the 7.5 hours it quotes for Vive Tracker 3.0.
Vive Ultimate Tracker is priced at $200 each, and the required USB-C dongle costs $40 extra. You'll want at least three trackers for body tracking, and HTC will sell you a three-pack with the dongle for $600. To actually attach Vive Ultimate Trackers to your body, you'll also want the TrackStraps by Rebuff Reality, which HTC is officially partnered with and sells from their website.
PC VR Beta Support
Vive Ultimate Trackers wirelessly connect to a USB-C dongle, which supports up to five trackers at once.
Until now, the USB-C dongle only supported HTC's standalone headsets, Vive XR Elite and Vive Focus 3. You could use Vive Ultimate Trackers in PC VR, but only via those two headsets' built-in PC VR Wi-Fi streaming feature.
But HTC has now launched a beta program for connecting the dongle directly to your PC to use with any PC VR headset.