WS1 is a converging/diverging nozzle.

Mine is actually .008" constriction, but they apparently average less.

It then bells out past bore diameter.

Beretta makes their skeet chokes this way also, at least in Mobil Choke and Optima.

It's a very effective choke for skeet.

WS2 is just a light modified, it's too tight for the second shot at skeet doubles except from 4, where it's perfect.

"The price of good shotgunnery is constant practice" - Fred Kimble