Hi - It depends on your application. i.e. whether the transducer is used in air or water. For air applications, usually there is no need to match the transducer to produce vibrations in air. But for water applications, it is very important to match the impedance of the transducer with impedance of water. It is not clear how and where this transducer will be used.
The following link is also very useful: http://www.ultrasoniccleaning-transducer.com/sale-9365021-20-khz-100w-high-power-ultrasonic-transducer-for-ultrasonic-tank-cleaner.html