Essentially little wireless earbuds that take this whole noise-cancelling thing to a whole new level. I have the first ones and they're pretty remarkable, already preordered the new ones which extend well beyond simple novelty.
You can turn down engine hum, but keep voices/stop announcements at full volume. The new ones apparently also let you layer in music from your phone, which was the obvious feature ommission from the first version. Allegedly the new one they're also playing with directional filtering, live language translation (?!), ML-based baby/siren/annoying coworker cancelling, and tons of other stuff. I haven't been this excited about a technology for years, as you might be able to tell :)
I could play music, but sometimes I like the roar of silence.