The 44 probe sheath is one of the two types we offer for your pressuremeter tests. The choice of the type of probe is made according to two criteria: the precision and easy maintenance. The coaxial probe gives more precise results than a twin probe. However, a twin probe shows a significant ease of maintenance of the tubulars. The user can choose a probe adapted to his tool (tubulars available), to his use and his skills. Here are the different uses of the sheaths for 44 probes: Rubber sheath 4mm : for low resistance, very homogeneous formations and flow pressure under 50 bars. 44 HR reinforced sheaths : for resistant, slightly homogeneous formations and flow pressure for 40 to 80 bars.