I live in the desert of Southern California. I have worn the vest (so far) on 3 rides for a total of 4-500 miles. Each of the rides was on an August afternoon of about 100 degrees. The vest turned each of these trips a pleasantly cool and enjoyable experience instead of the summertime hot, sticky and sweaty ordeal I have come to expect.
This item is a must have for summer riding in a hot climate.
I purchased this vest just prior to riding to Knoxville Tennessee, in July. We ended up in a heat wave with heat indexes in the 100's. This vest worked its magic keeping my core cool while riding. There were 5 of us riding, 3 purchased prior to going and two purchased these while we were there. We were very happy with our purchase and told several people while we there about the vests. Amazing though not many people were aware of them. We found that while riding if we recharged the vest after a couple of hours of riding seemed to keep the vest working at its optimum. Highly recommended for hot weather riding.