First of all, it costs transaction cost for the manufacturer to purchase intermediate products in the market. It includes the cost of seeking suitable suppliers, signing contracts and supervising contract execution. If the manufacturer can produce some intermediate products within the enterprise itself, it can eliminate or reduce some transaction costs, and can better guarantee the quality of the products. Second, if the manufacturers need is a special type of specialized equipment, the supplier does not generally willing to specialize in only a buyer of the product of the investment and production, because this kind of proprietary investment risk is bigger. Therefore, vendors that need this specialized device need to solve the problem of specialized devices within the enterprise. In the end, the manufacturers hire employees with specialized skills, such as specialized product design, cost management, and quality control, and establish long-term contractual relationships with them. This can be more beneficial than buying the corresponding services from other vendors, thereby eliminating or reducing the corresponding transaction costs. Fabricated and installed by Dortech Architectural Systems Ltd, Senior’s patented PURe® aluminium folding sliding doors feature as part of a stunning extension to Ms Stephen’s home. Offering slim sightlines that maximise views of the property’s pretty garden, the narrow yet robust aluminium frames of the PURe® doors have been powder-coated to provide an attractive brown finish that further complements and connects with the outdoor space. Famous British economist hicks and others argue that the above theory did not consider the factor of income, and therefore unable to determine the level of interest rates, in 1937, and puts forward the is-lm model on the basis of general equilibrium theory. It establishes a theory of interest rates and income at the same time that the four factors of savings and investment, money supply and monetary demand interact. Maintain a "buy" rating "If there is no allow most of the European Union oriented financial services agreement, the financial sector accounts for about 7% of GDP, but about 10% of tax revenue and 14% of the exports, may be affected by the special Britain will stay there," the report said.