Good product for growers - Cosytex
For the larger scale grower - We have been using Cosytex this year - it's great stuff. Better than fleece - good for winter salads outside (in the south west..) Currently have lettuce, spinach, oriental greens parsley and brassicas under it. (Alone for brassicas or over cloche hoops for leaf crops). Have used it to protect against all the flying beasties from carrot fly to cabbage white to pigeons.
We got an 8m x 200m roll, but it's easily 'cut and sealed' with a blow torch and fixed with anything from old bricks to tri-pegs. Most of our beds are 15mx 1.25m or 15m x 3m. we have the equivalent of 80 of the former size plus paths 0.5m wide between them.