Overall barrier property of reusable shopping bag package is not equal to that of material. Barrier property of non woven bag which is made of high barrier property material is unnecessarily good. Sealing place of school backpack and connecting place of bottle body and bottle cap are the weak points of overall barrier property of non woven shopping bag, and are places easy to appear leakage. At present, the understanding of reusable shopping bag is rather one-sided. Material test is highly valued while importance of overall barrier property is not fully realized, which is related with the slow development of transmission instruments and non woven bag test methods. The TOY serial oxygen transmission instruments introduced by Labthink can perform oxygen transmission testing of film and school backpack in required positions with excellent test results. Labthink has also realized the overall transmission non woven shopping bag testing of carbon dioxide. http://www.niceindustry.com/hot_new.asp Except vacuum reusable shopping bag, there are certain remnant gases existing in inner package, which (especially oxygen) will impose influences on some sensitive products. That is why the processing of remnant gases becomes extremely important. Modified gas non woven bag and vacuum package are widely used in packages with high deoxygenation requirements. Moreover, adding deoxygenation elements in the school backpack material can greatly increase oxygen barrier property of materials as well as absorb the remnant oxygen of inner package. Gas content (at present, only oxygen and carbon dioxide can be tested) of non woven shopping bag top space can be tested with headspace analyzer. However, the test precision is not high and it is only used as an assistant test.