You probably need to know the water pressure measured in PSI at the end of your hose where you want to attach the wand.
http://www.homedepot.com/p/3-4...
You might not have enough pressure for any of them to work properly! It is not only the number of holes but the size of the holes in the wand that will matter. Having a smaller hose will increase the pressure, but it will also reduce the volume of water going through it.
