This is a 5L professional cycling backpack with 2L water bladder,capable for storing most necessaries for outdoor activities, suitable for riding, running and mountaineering etc. Features： WATER SUPPLEMENT--Environmental TPU hydration bladder equipped, pressure-tolerant and leak-proof. Drinking the water by the tube directly without taking your running vest off or stopping your steps. SAFETY--Designed with reflective strips on the back and the front that is conspicuous in the dark straps to keep you safe. BREATHABLE--Excellent air ventilation system consist of porous mesh back and comfortable cellular cushion，prevents stuffiness and releases pressure to your back. LIGHTWEIGHT--Ultralight backpack with wide,adjustable and breathable shoulder straps distribute weight effectively, reduces strength consumption. The backpack with 2L water bladder provides you the max support,min burden and more convenience. LARGE CAPACITY--Spacious compartments with 5L loading capacity is large enough for storing most daily needs such as laptop, tablet, purse, books, cellphone, water-bottle and umbrella etc. VERSATILE--Suitable for all kinds of outdoor activities include riding, running, cycling,camping,hiking, mountaineering, outing, or excursions etc. Specification： Color: Black/Red/Gray (Optional) Backpack capacity: 5L Water Bladder capacity: 2L Material: Polyester,TPU Package size: 40*27*4cm/15.7*10.6*1.6in Package weight: 360g/12.7oz Package List： 1* Backpack 1* Water Bladder