Clamp-on ultrasonic flowmeter comprising: A measuring tube designed to conduct a medium; A pair of ultrasonic transducers, which are arranged on the measuring tube in a manner in which they are offset in relation to one another along a measuring tube axis; An electronic measuring/operating circuit designed to operate the ultrasonic transducers and to generate flow measured values of the medium, wherein each ultrasonic transducer has at least a transducer element designed to generate and detect ultrasonic signals, and a coupling element, wherein the transducer element is arranged on a first side of the coupling element facing away from the measuring tube, and wherein the coupling element is designed to be coupled acoustically with the measuring tube by means of a second side of the coupling element facing towards the measuring tube and to transmit ultrasonic signals between the transducer element and the measuring tube and vice versa, wherein the ultrasonic flowmeter for at least a first ultrasonic transducer (10.1) of the pair has an adjustment unit designed to adjust the ultrasonic transducer, wherein the adjustment unit is arranged between the transducer element and the first side of the coupling element or between the measuring tube and the second side of the coupling element and has a coupling surface that faces towards the measuring tube, wherein the adjustment unit is designed to modify at least an angle of a signal path in relation to the coupling surface and/or a signal path length, wherein the adjustment unit is coupled acoustically and mechanically with the coupling element and the transducer element or the measuring tube, characterized in that the adjustment unit has at least two degrees of freedom, wherein the transducer element has a segmentation in segments (11.1), wherein each segment can be activated individually, wherein the segmentation is particularly an angular segmentation or a linear segmentation along the measuring tube axis, and/or wherein the adjustment unit has a deformable element and a deformation unit, wherein the shape of the deformable element can be set directly or indirectly by the deformation unit, wherein the deformation unit has, for example, a screw apparatus (23.1) or an actuator unit (23.2). A measuring tube designed to conduct a medium; A pair of ultrasonic transducers, which are arranged on the measuring tube in a manner in which they are offset in relation to one another along a measuring tube axis; An electronic measuring/operating circuit designed to operate the ultrasonic transducers and to generate flow measured values of the medium, wherein each ultrasonic transducer has at least a transducer element designed to generate and detect ultrasonic signals, and a coupling element, wherein the transducer element is arranged on a first side of the coupling element facing away from the measuring tube, and wherein the coupling element is designed to be coupled acoustically with the measuring tube by means of a second side of the coupling element facing towards the measuring tube and to transmit ultrasonic signals between the transducer element and the measuring tube and vice versa, wherein the ultrasonic flowmeter for at least a first ultrasonic transducer (10.1) of the pair has an adjustment unit designed to adjust the ultrasonic transducer, wherein the adjustment unit is arranged between the transducer element and the first side of the coupling element or between the measuring tube and the second side of the coupling element and has a coupling surface that faces towards the measuring tube, wherein the adjustment unit is designed to modify at least an angle of a signal path in relation to the coupling surface and/or a signal path length, wherein the adjustment unit is coupled acoustically and mechanically with the coupling element and the transducer element or the measuring tube, characterized in that the adjustment unit has at least two degrees of freedom, wherein the transducer element has a segmentation in segments (11.1), wherein each segment can be activated individually, wherein the segmentation is particularly an angular segmentation or a linear segmentation along the measuring tube axis, and/or wherein the adjustment unit has a deformable element and a deformation unit, wherein the shape of the deformable element can be set directly or indirectly by the deformation unit, wherein the deformation unit has, for example, a screw apparatus (23.1) or an actuator unit (23.2).