Aonijie products aims to accompany your trip of Jogging, Running, Marathon, Hiking, Climbing, Cycling, Walking, Backpacking, etc. Make your outdoors time enjoyable and comfortable! Multiple Storage Compartment Designed with large capacity, you can store all tiny items such as a vacuum cup, keys, wallet, phone, and cash, etc. There's ample room up front for another bottle, wallet, keys, and other small items. Multifunctional design Offers a range of adjustments for a custom fit and increased stability.Under 6.8inches phone bin500ml kettle binRunning hydration backpack vest with Reflective strip,Provide safety for night running enthusiasts. Details design There are many details in the design of the backpack. The first is the whistle, which can increase the steady of cross-country running; the second is the keychain design, which can firmly fix the key and prevent the key from losing; the last is the fixed rope design at the kettle to avoid the violent shaking of the kettle during running. Add a comfortable experience to running. Lightweight and comfortable Snug form fitting bounce free fit. Apparel-like fit with a lightweight, breathable structure – equipped with Soft-touch, no chafe elastic perimeter binding Perfect for Marathons, Trail Running, Hiking, Cycling, Climbing, Outdoor enthusiasts, and Hydration-on-the-go! Light is fast, fast is beautiful. 3 Size S/M Recommended chest circumference 78cm-90cm/ 30.7-35.4in, M/L Recommended chest circumference 90-102cm/35.4-40.15in , L-XL Recommended chest circumference 102-115cm/40.15-45.27in