This is a shaped like a large key with a squared oval handle about 5 cm × 8 cm, and two thin metal strips, approximately 10 cm long, 5 cm wide, and 0.5 cm thick, descending in tandem from the center of the handle.
The two strips are spread open and then wiggled into the space between the cork and the bottle on either side.
Once fully in place, a turn and pull of the handle causes friction to turn the cork and pull it out of the bottle. "Ah-so" is a translation of the German title, "Ach so!", an expression meaning roughly "Ah, I see."
It is named so because its appearance often baffles people, but when its use is demonstrated, they often exclaim "Ah! So that's how it works". The ah-so is useful in opening old bottles with brittle corks, because it does not puncture the cork, limiting the likelihood of a brittle cork crumbling into the wine.
I've seen some such advertised before but never got around to getting one. Oh well, I've a fine-mesh tea strainer if the waiters' friend results in bits of cork floating in the bottle.
McWilliams was giving one of these away with every doz of 96 Lovedale, to make it easier to get the old crappy corks out. You just need to make sure you dont push the cork in the bottle!
Bruce
When not drinking a fine red, I'm a cardboard claret man!