Sprinkler Donut

Fill to the top with concrete, attach the top, let cure for a day, install! We have a very large yard with 130 sprinklers. Concrete donuts for all of them would have been over 2 grand! So I designed these, and I get a little over 6 assemblies per 1 kg spool. With the most inexpensive Olive Green I could find ($14 USD per 1kg spool) these cost less than 3 bucks apiece, counting the concrete! Be sure and fill to the top, so driving over them won't hurt them! I used high strength concrete. To keep track of all these sprinklers I put the station number followed by the stations' sprinkler number; that's what that number is.