Is this a hose fitting or something? What is it for? Fuel? Vacuum/Boost? If it's either of those, your best bet is to buy an AN fitting since you can find those in pretty much any style and thread you need.
Oh, I almost forgot.........Home Depot has a decent selection of fittings. If you are just looking for 1/8MNPT x 1/8MNPT, they should have it in brass. If you are looking for metric to male NPT adapter , they probably won't have it.