I made the holes to fit 3 mm screws but out door deck screws should fit too.

I was tired of buying new sprinklers every week i had the lawn mowed so i made these.
They make the sprinklers spray easier and the mower can see them easier to not run them over. and if he does, the mower blades skipp over the sprinklers. They seem to take 4 or 5 blade hits before they break. But some heat and acetone and they are back together.