KUKOME Mountain Bike Cycling Backpack Waterproof Men Women Lightweight Helmet Hydration Pack 12L Nylon Streamlined to reduce wind resistance. High Water repellent nylon fabric. KAM buckle at minus 40 degrees celsius to 50 degrees celsius is still high strength and long life. Back storage bag: Storing belongings safe storage. Small storage bag can be placed, a small PDA, Breathable strap: humanized design easy to travel.. Headphone jack: A pleasant trip Adjustment buckle design: belt and chest strap can be adjusted according to different populations.