i was planning on oredering this gauge but have ni idea what size fittings i would need to hook this to my fuel filter. The back of the guage according to the website "features 1/8'' NPT center back connection." I did a search and found nothing. I have a 94 civic hatchback. thanks for your help.

 

I'm pretty sure that it is 1/8" npt. You could always just get the B&M gauge, don't know what the yprice difference is, but I like mine.