It really works, it supported my 1-liter water bottle, cellphone, keys, and a gym towel, and there is still a good space. (I didn't take a photo at the gym, but it's the example one.) The negative point is the delay from the Brazilian post office, it got stuck in Curitiba for days, stopped at customs, and they charged me 90 reais to release it. Ah, and a question, what is the purpose of the zipper's inner hook for??? ?