I used 2" extra heavy duty knotted netting from Pinnon Hatch Farms.
https://www.pinnonhatch.com/Poultry-Netting-Heavy-Nets
He sells it in smaller dimensions on eBay.
I went with 2" because where I was living we got the occasional heavy snowfall. Now I've moved somewhere where snow is rare but 2" is still good for not building up leaves and sticks.
I use airline cable and 2x2 posts to hold the netting up since my run is not framed (it is welded wire dog kennel panels).
ETA I see that it is the same as the netting The Phantom posted.