Wanted to bring my cellphone with me on a 25-mile skate marathon but didn't have room in the little zip pouch on my water bottle belt for the phone _and_ the energy gels _and_ the skate tool. My regular phone holster/clip didn't have a flap to secure the phone, so that clearly wasn't going to work. The Timbuk2 pouch clamped securely around the belt of the water bottle holder and allowed me to attach the phone flush against my waist in a horizontal position so that it wouldn't interfere with arm-swing. If they'd put another square centimeter of velcro on the flap to make this really bombproof, I'd have given it 5 stars. In any case it did the job just fine and my phone was never in any danger of falling out.