After comparing this with my Trekz Titanium, I can say that this successor to the Trekz Titanium is definitely their best model yet. It's lighter, runs on Bluetooth 4.2, and sounds better.
No More Plastic
In order to make the unit lighter, Aftershokz have completely done away with the plastic part of the frame, making the only plastic the electronics on the sides. The form factor is almost identical to the Trekz Titanium, except for the fact that it is 20% lighter, has a complete titanium frame, and has the headphones curving up a little. This makes for a slight downward curve in the frame, which at first may seem awkward, but that will make it fit more easily with smart-glasses, for example.
To be honest, I thought the Trekz Titanium sounded pretty impressive. But the Trekz Air sound noticeably better, with a bit more base and less clipping at louder volumes. The microphones are also improved while on a call, so that should mean less muffled sound coming across the line.
The only bad part is that the battery is still the same 6 hour battery from the previous unit. Actually on second thought, it's pretty impressive that they were able to pull that off with this lighter model, considering the fact they did need to use a smaller battery. They went for a smaller yet more power-efficient battery, which managed to be able to last 6 hours, so that is definitely not a strike against them.
I would highly recommend these headphones if you're looking for a comfortable pair of headphones that sound good, allow you to hear the world around you, and are durable, then look no further than the Trekz Air.