The Adv Skin 5 Set has a total capacity of 5 liters. It keeps two 500 ml bottles right where you need them, and allows for other essentials to be carried, too. hone, energy gels, keys, a windbreaker, etc. are carried snugly around your body, with minimal shaking, rolling and rattling. - Two bottle pockets and two bottles included - The bottles flatten as you drink --> no air pockets, no sloshing - One bottle pocket has a small zipper pocket - SensiFit structure for a great, shake-free fit - Main compartment for gels, a windbreaker etc. Choose the size according to your chest circumference: - 80-85 cm: XXS - 85-91 cm: XS - 91-97 cm: S - 97-103 cm: M - 103-109 cm: L - 109-118 cm: XL