LIGHTWEIGHT - The hydration backpack is made of quality polyester material which is endurable and light, this professional cycling bag design is different from other backpacks that are a larger figure, it is simple and super lightweight that is good for outdoor activities. BREATHABLE - Excellent air ventilation system consists of porous mesh back and comfortable cellular cushion prevents stuffiness and releases pressure to your back. LARGE CAPACITY - 5L running backpack is large enough for storing most daily needs such as laptop, tablet, purse, books, cellphone, water bottle and umbrella, etc. ADJUSTABLE - Adjustable waist strap and front strap can adapt to different sizes, you can make the backpack fit you perfectly and keep the pack from moving. SAFETY - Our running backpack is designed with reflective strips on the back and the front that is conspicuous in the dark straps to keep you safe. Our hydration backpack is a great choice for riding, running and mountaineering, etc. It's also a great gift for Christmas, birthday gift and other holidays gift.