Ultrasonic transducer for use in an ultrasonic flowmeter to measure the flow velocity or volume flow of media in a measuring tube, or in an ultrasonic flow measuring device to measure the level of media in a vessel, said transducer comprising: at least one transducer element for the generation and/or detection of ultrasonic signals; and at least an acoustic transformer, wherein the acoustic transformer is acoustically and mechanically coupled to the transducer element; and wherein the acoustic transformer has a radiation surface and a longitudinal axis which intersects the radiation surface; and at least a housing with at least a housing body, wherein said housing body has at least a housing chamber with a housing wall, wherein said housing wall at least partially surrounds the acoustic transformer, wherein the housing is connected acoustically and mechanically to a measuring tube wall or a vessel wall, wherein the acoustic transformer is mechanically connected to the housing via a lateral surface of the acoustic transformer by means of a first acoustic annular isolation, wherein said first acoustic isolation can be exposed to the medium, wherein the first acoustic isolation has a first isolator and a second isolator and a third isolator, wherein the first isolator is in contact with the acoustic transformer and the third isolator is in contact with the housing and wherein the second isolator is arranged between the first isolator and the third isolator, characterized in that the second isolator is at least partially held by the first isolator and the third isolator, wherein the first isolator and the third isolator are radially clamped, and the second isolator is mounted in a manner in which it can oscillate. at least one transducer element for the generation and/or detection of ultrasonic signals; and at least an acoustic transformer, wherein the acoustic transformer is acoustically and mechanically coupled to the transducer element; and wherein the acoustic transformer has a radiation surface and a longitudinal axis which intersects the radiation surface; and at least a housing with at least a housing body, wherein said housing body has at least a housing chamber with a housing wall, wherein said housing wall at least partially surrounds the acoustic transformer, wherein the housing is connected acoustically and mechanically to a measuring tube wall or a vessel wall, wherein the acoustic transformer is mechanically connected to the housing via a lateral surface of the acoustic transformer by means of a first acoustic annular isolation, wherein said first acoustic isolation can be exposed to the medium, wherein the first acoustic isolation has a first isolator and a second isolator and a third isolator, wherein the first isolator is in contact with the acoustic transformer and the third isolator is in contact with the housing and wherein the second isolator is arranged between the first isolator and the third isolator, characterized in that the second isolator is at least partially held by the first isolator and the third isolator, wherein the first isolator and the third isolator are radially clamped, and the second isolator is mounted in a manner in which it can oscillate.