The hat has Permethrin applied to it. I was at a meeting today and talked to a person from Sawyer was touting his wares. http://www.sawyerproducts.com/

He spent a pretty good amount of time explaining things to me in regards to repellents and such. The hat by itself is only part of a defense against the various bugs. You would have to have shirts, hat and pants treated in order to have optimum protection. It would protect even non covered areas as the face. Permethrin is good against mosquitos, flies gnats and such. It has broader coverage than DEET. Permethrin does not last long on skin and therefore should be applied as directed on clothing. Naturally, they sell a permethrin spray.

The products apparently can be washed and maintain effectiveness for some period of time/number of washings. I do not know how effective it is after washings. I used permethrin sprays one time on an African trip and had no difficulties.

Sawyer sell all sorts of different sun screens and insect repellents. Apparently, they will have a new water filtration system that will be pretty interesting.