Threads to what is termed a "3/8 Flare Nut" fitting.
We use this fitting to connect 3/8 copper pipe to the gas regulator on a caravan (Tapered 3/8 thread).
No thread tape or similar on the flare connection as it seats against the other taper, the tapered thread needs thread tape or similar sealant.
Made in Australia. Should be fitted by a suitably qualified person.
Brass Gas Fitting 3-8 Male Flare X 3-8 MBSP With Test Point With Fibre Washer