Happymodel CruxF405HD is a board with ESCs, flight controller and receiver in one. The base of the board is a ICM42688P gyro supporting a refresh rate of up to 8KHz and a F405 processor. The board supports 2-4S Lipo battery power and current up to 20A. The ESCs use Bluejay firmware. It is particularly suited for building lightweight 2-3" copters. The board includes a barometer BMP280 for height measurement, 8MB memory for blackbox and current sensor. There is also an integrated connector on the board for digital video transmissions.

A big advantage of the board is the integrated ELRS receiver, which is connected via UART. Classic integrated receivers are connected via SPI bus and their firmware is included in Betaflight. The UART receiver is a full-featured classic Happymodel EP1 receiver that can be updated or set up separately via Wifi. The ELRS receiver is connected to UART2. By disconnecting the pins, the ELRS receiver can be disabled and use the UART to connect another device. The antenna is connected to the ELRS receiver via the IPEX connector.