that... is what i posted above, but yours cost more .. so is -4 an the same thread as 1/8 npt ?
npt is thread seal an(-an) is standardized thread ranging, with a tapered seal at the end (comrpession fitting)
To clarify this a little more for someone that might not understand:
NPT is National Pipe Thread and is a tapered thread. The outside diameter at the end of the thread is smaller than the outside diameter at the base of the thread, so it looks like a threaded cone. The female mate is opposite ie the hole gets smaller the deeper it goes. These types of seals it is good to use teflon tape or pipe dope.
AN has SAE or straight threads, like bolt outside diameter of the threads stay the same size from beginning to end. The taper at the end of the fitting meets a matching taper inside the female part so seal, the threads have absolutely no effect on sealing aside from profiding holding force. These fittings DO NOT need teflon tape or any kind of pipe dope (even though I see it every time I walk into a customer's plant
)
the number -4, -8 etc. is common sizing and it is the size in the number of sixteenths. -4 = 4/16 or 1/4" -8 = 8/16 or 1/2" etc. This usually refers to the inside diameter of the hole, or id. Except tubing then it refers to the outside diameter or OD.
I like those pictures though, good visual reference for pulling fittings out of a bin.