Brass Connector / Fitting - One way check valve
This is a very nice in line check valve that has female 1/4" NPT threads on one side and a hose barb for 1/2 inch ID hose on the other. These would be great for boat, race car, tractor, construction equipment fuel lines or anything else you want going one way but not the other. Flow is in the direction from the hose to the threads. In other words, you can only blow through the 1/2" barbed hose end, not the threaded end.