Fit's a regular 3/8's wrench. The extra holes are to give it some extra cranking power if needed. I find loosing up the dirt around very tight ones helps.
Recommend 3-4 outer walls and a thick infill 40%+ for max cranking power.
This sprinkler here:
https://www.lowes.com/pd/Rain-Bird-24-ft-45-ft-Adjustable-Pop-up-Impact-Sprinkler/3118641
The author marked this model as their own original creation.