This rim is built specifically for the rigorous demand a unicycle puts on a rim. Its the same rim as the double walled eyeletted alloy rim.
Should you want to build the wheel, here is a link to the Spoke Calculator so you can find the correct spoke length you need.
Spoke Holes: 36
Material: High Quality 6061 heat treated aluminum with box section
Finish: Racing green powdercoat
Nipple Eyelets: Stainless Steel