3-digit 0.56' Red LED 3.5-30V DC Voltage Meter w/ High and Low Voltage Flash + Buzzer Alarm - Black
Can make the voltage meter below or above a figure value to flicker and buzzer alarm. The alarm value can be adjusted. The default is up to 30V low to 11V. The alarm value specific adjusted method: Http://ajw7yupjhk.l18.yunpan.cn/lk/QX8JJajkU26Tv