features oxford outer layer and nylon lining, adjustable straps, 2/5cm round opening and D-rings to front. Durable and convenient for running, cycling, hiking, and camping. Features: 600D oxford outer layer and 420D nylon lining, water-repellent, wear-resistant and durable for different seasons and places. Water bladder compartment fits for 3L water bladder. Top round opening with diameter of 2/5cm. Adjustable shoulder straps and adjustable chest straps with quick-release buckles to fit your body size and keep stable while walking. Foamed back is comfortable to wear, allows effective ventilation and moisture-wicking. Front soft handle to carrying and D-rings for attaching to outdoor vest. 3L TPU water bladder is featured with quick disconnect bite valve, extra-large water inlet, 100cm water tube with sleeve. Fits for hiking, camping, cycling, walking, running or other types of outdoor adventures.