SpigotMaster SM01.125 Vacuum Breaker is available at Amazon.com
It is made for fine-threaded spigots.The internal diameter is one inch.It comes with a standard vinyl hose washer.It was made in the USA.
It is made for fine-threaded spigots.1 is the Internal Diameter.It has a custom washer for the best fit and no leaks.It was made in the USA.