The closure mechanism on this backpack is a zipper. One of the materials used to make this bag is cotton and you can put various small items in the inner pocket.
From Amazon
Fjällräven Unisex's F23340-631 Haulpack No.1, Foliage Green, One Size
Parasol Store
Fjallraven Haulpack No.1 Foliage Green - ONE SIZE / Foliage Green