Review on Enhanced Performance: uxcell 5V 85dB Industrial Active Electronic Alarm Buzzer - Set of 15 by Jason Ampongan

I tested 3 kits out of 15 and none of them worked at 5VDC. They sometimes worked at higher voltages like 9 or 12 VDC but were not reliable. I wasted my time fitting the part into a model airplane (should have tested it first) only to find out it didn't work and had to cancel the order and now I'm looking for a replacement part. I'm assuming this is a production line defect, hence they have ambiguous 5VDC and 6-24VDC voltage ratings.