There are different features of the product liability law. A design defect is when there is an error in the basic design of a product such that all copies of that product, each unit of the product, are going to have the same defect. A manufacturing defect is different. That means that that one particular unit may have been mismanufactured in some way. There may be a metal component that was not structurally sound. Something about the manufacturing process. Finally, the labeling, the warning requirements, stand alone and those lack of a reasonable warning can make an otherwise safe product into a defective product.