Attention:This link is ML Size backpack.If you need SM and LXL size ,please check it at below links:
AONIJIE 18L Hydration Backpack:
Move freely and carry everything you need for a day on the trail.
Head out for an all-day trail run or a technical hike: the 18L backpack efficiently carries your full kit. Lightweight and comfortable, this bag makes sure you're fully prepared for several hours of active adventure.
Item:Running Hydrattion Bakcpack
Fabric 2:85% nylon,15% spandex
Fabric 3: 85% nylon,15% spandex
S/M Recommended Chest Circumference: 72-96cm
M/L Recommended Chest Circumference:94-108cm
L/XL Recommended Chest Circumference: 106-120cm