Well designed. The alarm is quite loud. It beeps twice when you plug in your battery. I hold my meaty finger over the buzzer to muffle it so I don't startle everybody around me. You can adjust the voltage at which the alarm goes off, which is just fantastic. Instructions for making the adjustment are printed in tiny tiny lettering on the back. The display is very bright, easily visible from short distance depending on your eye sight. The display cycles between showing the total voltage of your battery pack, then each individual cell. The display changes too quickly for my liking. It measures 39 x 25 x 11 mm, and weights 9.6, lets say 10 grams, which should be no problem for an under-powered 4-channel 400 size helicopter and probably still manageable for a 200. If they used smaller 7-segment LEDs, a single buzzer, and it only had the ability to read 1S to 4S packs, it could be a third of the weight. There is very little to complain about.I bought 3 of them - should have bought 12!

Save the LiPo battery with cut-off manually, when this device alarm. You can set the switching level for arming from 2.7V to 3.8V step 0.1V... Display voltage of any cell, and the total voltage of battery. The buzzer is loud, you can hear good from 100-200m on electric planes, and you can hear the overdischarged receiver battery alarm on gas/glow plane.