Speedybee F405 + 35A BLS Mini stack is a flight controller and ESC combination with excellent price/performance ratio suitable for 2-4" drones. The flight controller is packed with features. It is based on F405 processor with ICM42688P gyro. The main advantage of the board is the integrated bluetooth module for wireless setup, integrated barometer. There is a 5V and 9V BEC as well as 8MB of memory for the blackbox. An interesting feature is also the 4 LEDs on the edge of the board that indicate the battery status. This way you can see at a glance if you are putting a dead battery in the drone. The ESC can handle current up to 35A, voltage 3-6S and uses BlHeli_S firmware. The regulator includes a TVS diode to suppress unwanted voltage spikes.