The КОШ type ball check valve is designed for preventing the backflow of cementing slurry or drill fluid from the interstring space to the inner space of the casing string. In addition, the use of КОШ promotes partial washing and cleaning of the annular space. Standard sizes of the produced valves: КОШ2. 89, КОШ2. 102, КОШ2. 114, КОШ2. 127.