OUTERDO 10L Outdoor Sports Backpack Shoulder Belt Bag Waterproof Sports Hydration Pack for Biking Cycling Traveling Camping Hiking Size:11 * 24 * 45cm Capacity: 10L (water bag can hold 2-5L,water bag not included) High-strength nylon fabric honeycomb lattice and wire lattice. The back according to ergonomic principles, so that the spine from oppression and breathable. With belt and chest buckle plus bag, can be completely hands free. But also to replenish moisture, making riding more focused, more secure.