The SuperF405HDELRSAI0 flight controller integrates a UART 2.4GHz ExpressLRS receiver and a 20A Blheli_s ESC (pre-installed with firmware) that supports 3-4 batteries The larger Mosfet supports up to 20A of current and reserves a 6-pin socket for plug-and-play with for HD devices. This is a great solution for building 3-4S HD digital FPV calls Binding steps: 1. Power the flight controller via USB plug-in and unplug. When the red LED on the flight controller goes out, immediately disconnect the power supply and repeat the above steps again. When the FC is powered on for the third time, the red LED starts to flash double, indicating that the onboard receiver enters binding mode Binding steps: 2. Make sure your ExpressLRS tx high-frequency head module firmware is v3.x.x. Then go to ExpressLRS.lua from the "Tools" menu of the radio transmitter. Then click [Bind] to bind with the onboard ExpressLRS receiver. The red LED should flash slowly and then stay on, indicating successful binding. If the red indicator flashes three times after binding, please change the value of the Model Matching tab from "Off" to "On" or from "On" to "Off" Receiver LED status meaning: The red LED stays on to indicate successful binding or RC link establishment; the red LED double flashes to indicate entering the binding mode; the red LED flashes slowly to indicate that the TX module has no RC signal input; the red LED flashes quickly and continuously to indicate that the ExpressLRS wifi is enabled; the red LED flashes three times to indicate a model mismatch, and the model matching needs to be modified in ExpressLRS.lua Serial port description: The ELRS receiver is connected to UART2 by default when it leaves the factory. Usually UART1 is used for MSPOSD of high-definition image transmission such as for /WalksnaiI/HDZER0 UART6 can be used for GPS or other serial devices. IRX6 is an inverted serial RX6 for SBUS input. IRX6 and /RX6 cannot be used at the same time. Due to different batches, there may be differences in product appearance, color, and printed text, which not affect the use. Colour:As Shown Material:PCB+Plastic Package Contents: 1 * Flight Controller Kit Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.