It makes it easier to pump air in. Do you know of a place where to get one?Ummm...why do you think you need a fully threaded schrader tube to go ghetto tubeless? If your wheel is drilled for schrader, a standard 20" tube will work just fine. I don't understand why you would need a metal threaded schrader valve.
Are you talking about the Conti tubes I linked to? The Schrader options are definitely fully-threadedActually the tubes that scuver linked to are not threaded schraders, they are available in presta and schrader. Be cautious with this, most presta valves are fully threaded. Most schraders are not.