The buzzer is 92 dB while standing still, when spun a student can easily hear the shift in frequency Buzzer housing has a simple on/off switch and is constructed of rugged ABS plastic Nylon cord is 2'8" attached to a rugged ABS handle 8.5in long, 1in diameter) Battery not included The perfect demonstration of the Doppler effect in a classroom (with caution of course). Swing the Doppler effect apparatus and students will be able to hear the change in frequency. Battery not included.