Microsoft doubled down on its commitment to what it called “mixed reality” today at its Build developer conference, revealing motion controllers that work closely with VR headsets from Acer. With a $399 bundle containing all you need coming later this year, it could be one of the more affordable ways out there to get into the VR game.

We’ve seen Acer’s headset before — it was notable at the time that it used built-in cameras to both track objects and its own position in a room, HoloLens-style. That capability also powers the controllers — it’s called “inside-out,” by the way, as opposed to “outside-in,” which uses sensors in the room to track the device and headset.

“These motion controllers were perfectly designed to work with our mixed reality headsets,” said Microsoft’s Alex Kipman on stage at the conference. “If you can see your hands, we’re tracking them.”

That is to say, as long as your hands are in the field of view of the headset, they’re being tracked optically by the cameras on the front. The controllers themselves have rings of LEDs that provide six degrees of freedom; there’s also a trigger, thumbstick, and a tiny trackpad a la the Steam controller. They look a bit like the Oculus Touch controllers, but the “hoop” doesn’t loop around your hand.

Microsoft claims you’ll get sub-millimeter precision without complex setups like IR blasters or in-room cameras — it’s all in the headset and the controllers themselves.

Microsoft didn’t demo the controllers on stage, at least in reality — they did, however, have someone join a mixed reality conference between several Cirque du Soleil designers. It was a little corny, but it at least showed that somewhere, someone has working prototypes at least in their hands.

Developers have two headsets to choose from — a $300 Acer one and a $329 HP one, both of which you can order today. But if you’re smart, you’ll wait a little bit for the bundle coming this holiday season that includes a pair of controllers for $399 all day. That makes it cheaper than either Oculus or Vive — especially so with the latter.

Whether the headset and tracking are up to those standards, however, is another question. Hands-on experiences with the headsets have produced mixed impressions, and the controllers aren’t available for testing just yet. So while we can be happy that there’s an easy, relatively inexpensive way to jump into VR on Windows, it might be best to withhold judgment.