Components are approved in laboratory tests, including: fabric, buckles, straps, foam and zips. For example, for fabric: resistance to wear, tearing, colour-fastness in UV rays, washing, waterproofing, etc. A final test on the finished product simulates the kind of treatment to which it will be subjected over several years, to assess the strength of the assembly. The backpack is weighted then placed on a dummy which then reproduces the movement of fast walking through thousands of cycles.