Hobbypower KK2.1 LCD Flight Control Board 1.9S Firmware for Multirotor Flying Wing V-tail Generation KK2.1 board with updated sensors, memory, header pins, and hard case protection. The board comes with software version V1.9S for easy setup. The KK2 added polarity protection to the voltage sense header and a fuse protected buzzer outputs, in case something is accidentally plugged in incorrectly. The voltage sense line has been updated for better accuracy. The board is clearly labeled and the voltage sense line color has been changed to red for easy identification, making installation and connections a snap. The KK2 is next big evolution of the first generation KK flight control boards. The KK2 was engineered from the ground up to bring multi-rotor flight to everyone, not just the experts.