Hello Massdrop commununity. On behalf of AKRacing I want to apologize for the mistake on "tilt angle lock" with the Aero chair. It was a typo in the factory, someone put "yes" next to that spec when they should have put "no". It passed through my hands without catching it and through to Massdrop who reproduced what we gave them.
There seems to be a bit of confusion on exactly what this feature is. A chair that has this feature allows you to tilt back the seat and the backrest together and lock them in a tilted position, usually up to about 10 degrees. Some refer to this as "rock and lock" because it is part of the rocking function. Here is a photo of one of our Onyx chairs in tilt angle lock. Notice that both the seat and back rest are tilted and he is sitting in it without any effort to rock.
Only two models of AKRacing have this feature. It is not a high demand feature. All of our chairs have regular tilting (or rocking) and this feature is both lockable so the chair won't tilt and there is a tension adjustment so you can control how easy it is to rock. That means the Aero will rock or not based on your preferences. The only thing it will not do is lock in a tilted position as in this photo.
It will also recline, as in this photo:
It tilts back all the way to flat, 180 degrees, even if in this example he did not go that far back. The seat stays flat and the backrest reclines.
And, just for reference here is the same person in a normal seated straight-up position:
I hope this helps clarify. Again we apologize for this error. It is 100% our fault and not on Massdrop since we accidentally misinformed them. That said, the Aero is a great chair and those of you that opt to take it are going to be very happy in my estimation. If you have any questions, you can call us at 805-383-7005 during normal business hours on the West Coast.