This is an absolute must have for anyone with a quad that can go over 100m. You can get it here for only $7.
It comes with a servo connector to attach it to your FC, or you can solder it directly to a 5V output. A button on the end allows you so swap the colours of the two LEDs between red blue and green, or a combination of both. You can also set the lights to flash, pulse slowly, or simply stay on.
The buzzer works by detecting movement. If you crash your build and can’t find it in 90 seconds (assuming it is not moving), the buzzer will start beeping, and the LEDs will flash on and off.
This is seriously loud, and will be heard by anyone within a couple of hundred meters. To turn it of simply move your quad, or you can press the button on the end.