As far as I know, Aheadset is a brand name that is linked with the concept of the threadless headset. It was apparently once owned by Dia-Compe. I think Cane Creek now owns it. I have a modern Aheadset threadless headset for one of my cheaper mountain bikes. It's an inexpensive headset with a plastic top cap.

http://www.aheadset.com/

The only thing that seems odd with your setup is the stem that doesn't seem to have any pinch bolts. You use the top cap, bolt, and star washer inside the steerer tube to set and maintain preload on the headset bearings, but the stem needs to also fix itself to the steerer tube to steer the bike. Unless this particular headset was designed for that top bolt to be set so tight that it essentially holds the stem in position? I don't think I've seen that before, but I guess it's possible.