Cylinders, in cooperation with mortise locks, define the level of security of protected premises. The use of an appropriate cylinders affects the fluent and reliable operation of a mortise lock. The size of a cylinder consists of 2 elements, for example 30/30. It means that the distance between the face of the cylinder and the middle of the mounting screw hole is 30 mm and the distance between the middle of the mounting screw hole and the second face is also 30 mm.