The full-package guys seem to orbit around a tube or “jar” with a 3” opening and a thick, soft gasket. The “jar” can be a straight tube or a variant of a “sun tea jar”, or even a special two-piece plastic bell that screws together with wing nuts. They do that because once they get a full pump, gettng *out* of a tapered jar can be difficult.
The gasket is often left in place when the tube or jar is removed, working as a behind-the-balls cock ring to maintain the pump.
The Froehle tubes are a “anatomically correct” tubes that have a large ball pocket at the base of the tube. Topologically they’re full-package tubes; they just don’t have the huge expansion room of the larger tubes or jars. There’s not ball pinch because your balls are inside the pocket. Well, it helps if you’re partly flaccid when you enter, so they don’t get pinched going around the corner.
The big pumpers are all about the edema; they’re generally going for maximum package size, and they don’t worry about edema of the shaft. It’s also common to pump for hours at a time, generally around 3”Hg. The scrotum can swell to the point the shaft is buried; they call that “cock swallow.” You don’t have to do that, of course.
I think my Froehle tube rocks, but they’re expensive, you have to order them from the EU, and they’re cheaply made and you’ll have to add some silicone sealer to the gasket to keep it from leaking due to bad design. Someone could make some bucks doing a better design at a reasonable price.