Between my sprinkler system solenoid valve and indexing valve there is a T connector that adds some sort of metal piece on top of the pipe.
I could not find a similar part on any of the sprinkler system parts lists or guides I've looked through, and google searching for any of the writing on top didn't bring up anything. I can make out the letters CFM 13.5, which makes me think it may be some sort of regulator, but I don't see how that would work since it is attached on the side of the pipe.
The part leaks water when the system is turned on, which makes me think it may be broken and needs to be replaced. Any ideas what it is?