What is a file bag and what does it do?

Document belt, for their personal belongings or identity documents custody, data bags, white files. The style is divided into buckle type and article set type.
File bag classification: file bag, file bag, data bag, white file.
File bag function: used for their personal belongings or identity documents custody.
File bag material: PP material, PVC material, kraft paper.
File bag style: buckle, file cover, loose leaf bag, transparent side wide transparent file bag (A4, F/C).
Kraft paper bag thickness size: 150G, 250G, 350G, (3K, 4K that is A4, F/C).