comments:
Late_Tangelo3646 posted on r/irrigation1w
I have found a tone of these on my property as well, home is from the 50s larger 2 acre lot. It took a while to figure out. They are usually made of brass. Like the others have said they are quick couplers. I believe they use to be more common back in the day. They still make them though! https://www.amazon.com/Orbit-WaterMaster-Underground-51029-Coupler/dp/B000PSAQAG?th=1