Nathan Mutation Series X Trainer Mutation Waist Pack with 22-Ounce Bottle and 5-Ounce Nutrition Flask Limited stretch elasticized waistbelt 22 ounce (650 ml) hydration bottle with Quick clip Dual XTS cradles, reinforced with power stretch mesh Insulated holster allows access from right or left side 5 oz. (150 ml) nutrition flask in horizontal side holster