Last week I received large and medium mosquito head nets from PetersHeadNets and have had a chance to use both sizes on a dense thicket project with different sized hats.

Due to the elastic pull cord, I did not have a single problem with mosquitos getting in under the base. (The instructions recommend tucking the elastic base strap under the shirt collar.)

This brand of mosquito headnet is much better than all the others I've used over the years, in that the material allows for much better air flow and I can actually see out - through the material. This particular brand is, in my view, a significat improvement in every aspect of design and incorprates much more advanced material. The sewing is top notch.

If there is a "Holy Grail of headnets", IMHO this is it.