Specifications of self sealing plastic bags clear:

There is a concave and convex bone at the tight bag sealing, which can be automatically sealed. It can be sealed tightly with a single press. It can be opened and closed at any time. It is very convenient. The material is PE, soft to the touch, non-toxic and tasteless.

Compact bags are mainly used for product packaging, storage of food, jewelry, small parts, brochures, clothes, etc., with moisture, water, insects, to prevent things from scattering, induction.

http://www.polythene-bags.net/