Ultrasonic measuring cell for measuring the volume flow of a fluid flowing in a tube comprising • a continuous central recess having a longitudinal extension so that the central recess can receive the fluid-carrying tube; • at least six ultrasonic transducers; • at least two inlay regions (30, 40); • optionally at least two ultrasonic interrupter regions (90, 91); wherein at least a first and a second ultrasonic transducer (11, 12) are positioned on a first side of the central recess and at least a third and a fourth ultrasonic transducer (13, 14) are positioned on a second side of the central recess wherein the first side and the second side of the central recess are opposite to each other; wherein the first and the second ultrasonic transducer (11, 12) are aligned in a way that the first and/or the second ultrasonic transducer can emit a measuring signal oblique to the flow direction of a fluid in the tube to the third and/or the fourth ultrasonic transducer (13, 14) and can receive a measuring signal emitted oblique to the flow of the fluid in the tube by the third and/or fourth ultrasonic transducer; wherein no ultrasonic coupling gel or grease is between the fluid-carrying tube and the ultrasonic measuring cell;wherein a first inlay region is positioned on the first side of the central recess between the central recess and the first and the second ultrasonic transducer (11, 12), in a way that an ultrasonic signal received or emitted by the first and/or the second ultrasonic transducer (11, 12) passes at least partially the first inlay region; wherein a second inlay region is positioned on the second side of the central recess between the central recess and the third and fourth ultrasonic transducer (13, 14), in a way that an ultrasonic signal received or emitted by the third and/or the fourth ultrasonic transducer (13, 14) passes at least partially the second inlay region; wherein the fifth ultrasonic transducer is positioned on the first side of the central recess, wherein the first inlay region is situated between the fifth ultrasonic transducer and the central recess; wherein the sixth ultrasonic transducer is positioned on the second side of the central recess, wherein the second inlay region is situated between the sixth ultrasonic transducer and the central recess; wherein the fifth and the sixth ultrasonic transducers (15, 16) are positioned parallel to the central recess and opposite to each other; characterized in that the fifth and the sixth ultrasonic transducers (15, 16) have an intrinsic resonance frequency range between 0.5 MHz and 5 MHz and an impedance range of 6.5*10 6 Ns/m 3 - 30*10 6 Ns/m 3; and the ultrasonic measuring cell is configured to measure the propagation time of an ultrasonic signal inside the first inlay region and/or the second inlay region. • a continuous central recess having a longitudinal extension so that the central recess can receive the fluid-carrying tube; • at least six ultrasonic transducers; • at least two inlay regions (30, 40); • optionally at least two ultrasonic interrupter regions (90, 91); wherein at least a first and a second ultrasonic transducer (11, 12) are positioned on a first side of the central recess and at least a third and a fourth ultrasonic transducer (13, 14) are positioned on a second side of the central recess wherein the first side and the second side of the central recess are opposite to each other; wherein the first and the second ultrasonic transducer (11, 12) are aligned in a way that the first and/or the second ultrasonic transducer can emit a measuring signal oblique to the flow direction of a fluid in the tube to the third and/or the fourth ultrasonic transducer (13, 14) and can receive a measuring signal emitted oblique to the flow of the fluid in the tube by the third and/or fourth ultrasonic transducer; wherein no ultrasonic coupling gel or grease is between the fluid-carrying tube and the ultrasonic measuring cell;wherein a first inlay region is positioned on the first side of the central recess between the central recess and the first and the second ultrasonic transducer (11, 12), in a way that an ultrasonic signal received or emitted by the first and/or the second ultrasonic transducer (11, 12) passes at least partially the first inlay region; wherein a second inlay region is positioned on the second side of the central recess between the central recess and the third and fourth ultrasonic transducer (13, 14), in a way that an ultrasonic signal received or emitted by the third and/or the fourth ultrasonic transducer (13, 14) passes at least partially the second inlay region; wherein the fifth ultrasonic transducer is positioned on the first side of the central recess, wherein the first inlay region is situated between the fifth ultrasonic transducer and the central recess; wherein the sixth ultrasonic transducer is positioned on the second side of the central recess, wherein the second inlay region is situated between the sixth ultrasonic transducer and the central recess; wherein the fifth and the sixth ultrasonic transducers (15, 16) are positioned parallel to the central recess and opposite to each other; characterized in that the fifth and the sixth ultrasonic transducers (15, 16) have an intrinsic resonance frequency range between 0.5 MHz and 5 MHz and an impedance range of 6.5*10 6 Ns/m 3 - 30*10 6 Ns/m 3; and the ultrasonic measuring cell is configured to measure the propagation time of an ultrasonic signal inside the first inlay region and/or the second inlay region.