The product-in-hand contract entails the widest responsibility of the turnkey contractor, since he must not only complete the works so that they are capable of producing products of the quality and quantity stipulated in the contract, but he must also enable the purchaser to operate the works and achieve the production targets with the purchaser's own staff. The contractor is obligated to direct production and management of the works during an agreed test period, and the final take-over of the works occurs only after the works have been successfully operated during such a test period with the purchaser's own staff and by using raw materials and other materials which the purchaser would use.