It's a hip pack.  It's a sling bag.  Its Mountain Hip Pack 3.5L.  

MHP3.5 brings ultimate versatility, breathability, and durability to your daily active pursuits.  EVERGOODS breathable back panel is more breathable and more durable than spacer mesh.   3D patterning allows for locked in hip/waist wearing and is equally comfortable worn as a sling.  Intuitive zipper placements allow easy access to contents near the body.  MHP3.5 is ready for the trail or the town on bike, on foot, or however you choose.