Matek Systems 3-In-1 Battery Monitor Low Voltage Buzzer Alarm Discovery Buzzer Signal Loss Alarm Meter Monitor For FPV Multicopter Quadcopter It is a 3in1 gadget with 2--6S LiPo Battery monitor, Discovery buzzer Signal loss alarm functions. Compared to normal Battery Monitor, it's much more compact and lighter yet more powerful, it can be placed inside the frame thus well-protected , no need to look for your buzzer everywhere when your mini quad crash. Package includes 2pcs Twin loud buzzers, 85db each make you easily find your lost model Automatically alarms if loss signal for 1 minute, work with a CPPM signal Suitable for all kinds of Helicopters, multi-rotor, Cars etc. Size: 20x30x6mm,Weight: 7g.