Looks like I need to add some background info. I assumed everyone possessed Oxyhacker's books. My apologies. ; ) This adapter allows one to hook any 1/4" NPT air line, IP guage, medical O2 mask/flowmeter, etc. to a standard scuba first stage LP port. Therefor it's a male end like a reg hose fitting wih the o-ring on one side, and a 1/4" NPT female on the other. In both "The Oxygen Hackers Companion" and his reg book (both HIGHLY recommended by the way) it suggests using 1/4" female NPT to male flare fittings, grinding off the flare part and adding an o-ring. I did just that, but when the moment of truth arrived...the threads were incorrect. I'm sure I'm missing something simple here. I must be starting with the wrong fittings as the threads are course and not fine. Help please...