For some low and medium pressure hydrological tests, BAREF PAKER recommends Double Packers (IZ TYPE) from 28 to 170 mm. In this embodiment, two Pakers protect the test area and thus the test length (IZ) remains constant. Special connection equipments are added to two standard Pakers and they are connected with the help of two separate inflation unions. Thanks to the adjustable perforated pipes between the two packers, the desired test is performed on the area.