There is a concave-convex bone in the seal of the 28*40 bag, which can be sealed automatically. It will be sealed tightly once pressed easily. It can be opened and closed at any time, and can be used repeatedly. It is very convenient. The material is PE, tasteless, used for packaging, storing food ornament, cosmetics, frobnitz, instructions, clothes, etc. It is moisture-proof, waterproof, insect-proof, and prevents things from scattering.