The Camelbak Classic hydration backpack is great for when your activities span several hours. With it's low profile design and minimalist storage options the Classic doesn't interfere with a helmet. The external zip pocket will keep your keys and essentials handy and secure. The soft mesh harness is comfortable and breathable, especially after a long trail hike or bike. If you need to take a light wind breaker along the bungee cinch system can hold your extra clothing. Other Features: Material: Nylon Back panel: Mesh Volume: 162 Cubes Tube Insulated: No Reservoir Size: 70oz Pockets: One Dimensions: 17" x7.5" x 2" Valve: Big Bite self sealing Weight: 1lbs Warranty: 2 Years Use: Hiking and biking