I trained with a group for the Houston half marathon a couple of years ago & we all used Fuel Belts. I found it to be convenient b/c I could carry more than one type of fluid - water in a couple and some sort of sports drink in the others. With it being so hot in the summers here, I would freeze all but one of them overnight so that I had fluid available from the beginning, but the rest would stay cool as they thawed throughout my run. When the temperature started cooling in the fall & they didn't thaw as quickly, we'd fill the bottles halfway to freeze & then fill up the other half in the morning.