[koolba]

My Powershell-fu isn't quite up there. What's the first part of that block? Is that concatenating arrays of ranges of char codes?

[casselc]

Yes, it just creates an array of the decimal values for ASCII A-Za-z0-9. By default Get-Random just returns a random unsigned int, but if you pass in an array of objects it will select a random object from the array.