... .maintain the vacuum for longer time. 3.material: PP 4.ISO9001 2008 certification Plastic Vacuum Bags' Valve Features 1. material: PP, ... PE, POM 2. size: one size for each kind of valve 3. color: pink, green, blue, white, black, coffee, ... . certification: ISO9001-2008 5. kind: mini valve, mini Ninja valve, switch valve, slide valve, automotive valve 6. design and molding developed by Japan Function ...