The AST1109MLTRQ is a black Buzzer Transducer made of LCP plastic resin housing. The direct drive transducer device does not have any included DC circuitry, so the user must apply a sine or square wave with the appropriate rated frequency. A square wave will typically result in more sound level than a sine wave. The higher the peak-to-peak voltage applied (up to the maximum rated voltage), the higher the resulting sound level.