Features 1、This active buzzer has internal oscillation source, so it will alarm as long as being energized. 2、Convenient program control, single chip microcomputer high and low level can make it sound, better than a passive buzzer. 3、Module is driven with 9012 transistor. 4、Designed with holes for fixing with bolt, convenient to install. 5、External connection of 3.3V-5V voltage, can be directly connected to 5V micro-controller and 3.3V micro-controller. Specification Features: This active buzzer has internal oscillation source, so it will alarm as long as being energized. Convenient program control, single chip microcomputer high and low level can make it sound, better than a passive buzzer. Module is driven with 9012 transistor. Designed with holes for fixing with bolt, convenient to install. External connection of GND3 out external micro-controller IO port. Specifications: 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