Adapters or steel threaded connections are used in hydraulic systems to connect pipes, hoses and other components of different or the same size or type. They are widely used in systems where tightness and resistance to high pressure are necessary. Adapters are made of carbon steel, stainless steel. Carbon steel: the most commonly used material due to its strength and ability to withstand high pressure; stainless steel is used where there are wet or aggressive chemical environments, for example, at sea or in the chemical industry, to prevent corrosion. Adapters are produced in various threads that meet international ISO, SAE, DIN, EN standards.