You close this hiking backpack with a buckle. The material of choice for this bag is nylon and things you want to keep extra track of can go in the inner pocket.
From Amazon
Osprey Men's Sportlite, Pine Leaf Green, Medium/Large
Trekkinn
Osprey Sportlite 30l Backpack Green M-L
Hardloop
Osprey Sportlite 30 - Walking backpack Pine Leaf Green M/L