3.3-5V Passive Buzzer Alarm Module For Arduino Descriptions: Work Voltage: 3.3-5V With fixed bolt hole for easy installation PCB Dimension: 3.3 x 1.3cm DuPont line length: 21cm Module adopts 9012 transistor drive Feature: No oscillation source, need square wave (frequency 2K-5K ) to drive. Sound frequency control, you can make a "do re mi fa sol la si" effect. Pin Definitions: VCC : 3.3V-5V GND : The Ground I/O : I/O Interface of SCM Package included: 5 x Passive Buzzer Module 5 x 3pin DuPont line