What you see is what you get; this fitting converts 3/4" NPT threads to a female garden hose connection. The O-ring is included in the fitting, but if yours goes bad or you lose it, you can pick up another one at link.
We had to bring this piece in to complete the () to connect the Prevost Pipe to a garden hose.
Fittings can get complicated so if you're not sure what to get reach out to and they'll make sure everything works.