Skystars F4 + KO45 is an affordable stack for freestyle and racing copters. The control unit with F4 processor uses BMI270 gyro, has 16MB of memory for blackbox and 5V / 3A and 10V / 2A BEC. The unit also has a connector for connecting DJI FPV and OSD, so it can be conveniently used on copters with digital or analog video transmission. The pads for connecting LEDs in the corners of the unit are also nice. It is supplemented by a 45A controller with BlHeli_S firmware.