The Fupa SG 13 Thread on Glass Fupa #13 cup has a thread on brass insert-no more orings.  This comes standard with the 3/32 diffuser on it.  This is just one cup.

30-35 CFH Argon - 175 DC Max amps with 3/32" tungsten,  Prevent arcing Brass-clean tungsten-start arc at low amp.  Do Not overtighten.