PREMIUM MATERIAL: Made of firm, breathable, light and durable material. MULTIFUNCTIONAL POCKETS: Enough pockets and pouches that can store items like cell phone, keys, thin raincoat, 500ml soft water bottle, 1.5L hydration bladder and other items for outdoor activities. LIGHTWEIGHT, ADJUSTABLE VERSATILE: Fully adjustable and breathable design allows a full range of motion for all runners, joggers, bikers, kids and adults. Perfect for any outdoor activities such as running, cycling, walking, mountaineering and so on. COMFORTABLE FIT WITH SPECIAL DESIGN: This backpack gives a comfortable fit over sports gear and accommodates the majority of body sizes. Specifications: Type: Running Hydration Backpack Brand: AONIJIE Model: E906 .........S/M BLACK................L/XL BLACK Material: 100% Chinlon Color: Black Size: S/M (For chest circumference 80 - 97cm) Capacity: 5L Gender: Unisex Size: 41 * 39cm / 16 * 15in Net Weight: 230g / 240g Package Size: 32 * 13.5 * 6cm / 12.6 * 5.3 * 2.4in Package Weight: 342g / 12.1oz