They say the grid is 5" x 7", and not a physical barrier, but a visual one. Evidentaly these nets were developed for use at fish farms to keep catfish, salmon, etc. safe from predators.
I had a hawk slam into 1/2 inch hardware cloth a few days ago trying to get one of my quail. So the claims that they see 8X better than humans and therefore don't even try to get thru the netting is not true if you accept my sample size of one. Haha. Just my 2 cents!