Nathan Peak Insulated Waist Pack 18 oz/535 ml double-wall insulated and Hi-Viz reflective speed draw Flask with push-pull blast valve cap Double-Walled Flask construction keeps fluids cooler 20% longer than other insulated flasks Angled Flask holder allows for easy one-handed access and bounce-free ride Extended side panels hug the body comfortably for a perfect fit Expandable zippered stretch pocket keeps essentials protected ( Fits up to iPhone 7 Plus)