The first possibility is a defect that caused material from the supplier. In the process of purchasing materials from suppliers may have items that are not in accordance with the specifications that we requested. That is normal. However, to minimize the possibility of defects that caused the error is to choose the supplier that the supplier has a good track record in terms of quality, then a layer of material inspection income. If there is a lack of in accordance with specifications provided immediately do a claim against the supplier.