Recomend chest circumference:80-118cm / 38.58-42.52 inches This backpack can be used for more than just running. It is suitable for almost all outdoor activities such as hiking, riding, camping, marathon, etc. - Capacity: 15L - Material: nylon and polyester Super Lightweight: It is super lightweight, just 0.395kg, reducing your loading weight when you are running, you can carry more necessities you need. Notice: 1. The two holders are fitted to 600ml water bottle 2. The 2pcs x 600mlΒ water bottles on the pictures are included