Hey Guys (& Gals), I'm trying to order a couple of end stop couplings for my hose taps. I know this is going to sound daft but I can't remember how the sizes work. There's 1/2 inch & 1/4 inch threads. the side of the tap says 1/4 inch but the coupling I've just removed from it is 1/2 diameter. Any body clarify what I should be ordering?