I can't even remember the amount of sweat stoppers I've tried over the years (with no success), it has always been an issue for me as I'm a heavy sweater.
I'm happy to report, this is no longer an issue as this product put an end to this. Today I took it for a test run and I must say I'm impressed.
After 2 hour ride this cap was still holding and didn't let the sweat get into my eyes and my sunglasses stayed dry and clear of sweat smudge.

Usually on a workout like that, I'm going through 3 sweat bands from other brands, which is a big inconvenience.
This cap is very light and feels good on the head, it doesn't make it feel hot and it works great under the helmet.

Another benefit I found to this product over the usual sweat band is that since it covers your entire head, if you ever had
a bee or a wasp go in between the cracks of your helmet, it might prevent you from getting stung because of it.

I'm now going to retire all my previous sweat  gear and buy few of those to have a complete weekly coverage, although one might find it's enough
to have only 2 as this product can be manually washed and be ready to use in a matter of hours.

Good Job!