Features Internal Oscillation Source: This active alarm buzzer has an internal oscillation source, which will alarm as long as it is powered on, which is very convenient and practical. Easy To Use: The buzzer module has convenient program control, and the single-chip microcomputer can make it sound at high and low levels, which is better than passive buzzers. Easy Installation: This active alarm buzzer module is driven by a 9012 triode and is designed with bolt holes for easy installation. Applicable Voltage: This buzzer alarm is connected to 3.3V-5V voltage, which can be directly connected to 5V microcontroller and 3.3V microcontroller. GND3 is connected to an external microcontroller IO port. Intimate Service: We provide 7-day worry-free return and exchange service for all customers. If you have any questions about our active alarm buzzer module, you are welcome to contact us and we will serve you wholeheartedly. Specifications: Working Voltage: 3.3V-5V Module Interface: 3 wire system Size: 3.8*1.3cm/1.5*0.5in Quantity: 5pcs Weight: 4g(approx.) Package Includes: 5 x Buzzer Modules Package List