On Board Lipoly Low Voltage Alarm (2s~6s)

Simple to use Lipoly low voltage alarm that is small and light for on board use, plugs into balance lead for detecting low voltage on individual cells. A loud alarm will sound and LED will change from Green to Red if any individual cell drops to 3.3v or below. [the exact type of low voltage alarm may vary depending upon where we source this item].

Spec.
Lipoly Range: 2s~6s 
Size: 38x25x11mm 
Weight: 9g
Low Voltage Alarm Threshold: 3.3v (per cell)

Note: Such a small price to pay for peace of mind.  you just never know when a battery cell is going to go and is it worth loosing a plane?