The addressable RGB LED stripe can not only improve the visibility of the multicopter in the air, but also passes a lot of information about its state. In the FC, it is possible to program colors and blinking for various situations(battery low, flight mode, arm, etc.).
The price is for one diode (about 1 cm, one meter contains 96 LEDs). You can order any number of diodes because the tape can be divided by one diode.