In our life, the most improtant problem is shelf life. And now more and more shoppers like to use the shelf life to check the quality of the commodities.
  Such as the window and door hardware accessories, government never gives a definition or demand of window and door hardware accessories’shelf life, it means that window and door hardware accessories don’t have shelf life in office certification. Many merchants tall theri products’shelf life is several years, they tell a lie, because even theirselves don’t know their products can be used for how many years.
  So some people ask, window and door accessories don’t have any national shelf life, what is the standard of its quality.
  Window and door hardware accessories belong to physical structure products, so in the using, it will physical expend. The standard of window and door hardware accessories is it hasn’t physical expend when it is uesd by many times. So in usually, it will be fine in several or ten years.
  And eventhough it hasn’t quality ensure, but it can be maintained after sold out. When the products appear a problem after you have bought it, technicists will go your home and maintain it. So when we choose the window and door hardware accessories, we should choose the big brand and the maintain is good after selling.