These work fairly well for short term relief as indicated by others, but will need to be re-wet for best results on a long run. Do not exceed the ten minute recommended time by much after the initial soak or the gel particles may escape bleed out (voice of experience)and the tie will get very stiff.

Soak it good and put it on dripping. Even when it dries out, it protects you from the sun. I just did 3,000 miles with lots of hot desert days and this helped.

I use these in the summer heat of Central Texas. The lower the humidity, the more effective it is. I don't get but a few minutes of cooling on humid days (store it in the fridge) but on drier days, I'll enjoy an hour or more of cool comfort and recharge it when I make a stop. Gave it five stars because I'm happy with the product quality -- mine seems well made. And, under dry, hot conditions, it holds enough water to be effective for me. I think it's a nice little low-cost luxury and I'd buy it again.

They aren't worth anything. Just put some ice in a scarf and roll it up and put on your neck, works much better than these.