Oxy/Acetylene, Propane, air and shielding gas reels for service trucks and rig welders. Lifetime warranty. 0.5" minimum port size for maximum flow using half inch hoses. The gas port threads are 1/2"npt female and can easily be reduced to 3/8, 1/4" or other sizes. As far as we are aware we offer the largest ports and rotaries. Other designs neck down to 1/4" or 1/8" in the rotary joint even if they advertise 1/2" adapters.