Recently you kind folks helped me identify the device that was stuck on the outdoor faucet at my new place. It was only an issue because it leaks, so badly that nothing gets through the hose. We’re not talking a little dribble!
I have now bought two different replacement devices and have failed on both. First I bought another backflow preventer locally, but the female connection (to the spigot) was too small. Then I found something online that was just an adapter, no backflow prevention. I thought I could use that in conjunction with either the original or the one I bought locally, as long as it bridged the size gap. But it didn’t. In the process I have learned that what these adapters are “adapting” is fine thread to hose-style thread. All well and good but apparently I have the only faucet in creation that is not only fine thread but also the next size larger.
I’m guessing it is not kosher to replace an entire faucet/spigot at a rental property (though I’d ask my landlord if he were in the country). I think I am just out of luck unless someone here recognizes the problem. I have searched and searched and nothing seems to adapt two different SIZES*. In fact, measurements are not mentioned at all when it comes to these items. I’m a little bummed because, as I mentioned in the original thread, the location for this faucet is perfect for several tasks. But I’ll live! 
*Except, of course, the leaky thing I took off. One DOES exist. Maybe just that one!
