A container (200) for containing a coupling medium for transdermal delivery of a medicament and a transducer unit (100) for use with the container (200) are disclosed. The transducer unit (100) has a transducer (108) with an output face (110), and the container comprises a chamber (214) for receiving the coupling medium and a contact surface (212) for coupling for ultrasound transmission is formed between the output face (110) of the transducer (108) and the contact surface (212).
