What can I say, they work. I bought a six-pack to test them out on two golf hats. Both hats are dark blue, so stains should show up easily. I've worn both hats at least three times each in 90-100 degree weather. No sweat stains on either hat, and no sweat leaking through the material. The adhesive is a bit weak, and if you're not careful the liner will fall out of your hat if you shake your hat (to knock dust off for instance. Really the only knock on these is the price. If you've got 10-20 hats like me, and want to change these liners out after 4-5 wearings, you're gonna spend serious $$$ to keep restocking these. Otherwise, they do what they say they do.
Rating:
[4 of 5 Stars!]