The CrazyF411 ELRS flight controller comes with integrated UART 2.4GHz ExpressLRS receiver and 20A Blheli_s ESC( firmware pre-installed) which could support 2-4s. Bigger Mosfet could support high to 20A currents would be better for 2-4S toothpick drone or long range FPV drone. And because the 2.4GHz ExpressLRS receiver is equipped with the SX1280 radio frequency chip with high sensitivity, high packet rate and low latency, this flight controller is that all /Freestyle pilots needed. The built-in ELRS receiver is UART communication with MCU, it's the same like EP1 which you can update firmware by betaflight pass-through or WIFI, very simple. The default firmware is ELRS V3.0.1. This flight controller would be used for Crux35 to instead ELRS X1 flight controller. Flight controller MCU:STM32F411CEU6 (100MHZ, 512K FLASH) Sensor: ICM42688P or BMI270 (SPI Control) Mount pattern: 25.5x25.5 M2 Power supply: 2-4S Lipo battery Built-in 20A Blheli_s ESC each Built-in Betaflight OSD(SPI Control) Built-in UART ExpressLRS 2.4GHz receiver Built-in 5V 1.5A BEC Flight controller firmware target: CRAZYBEEF4DX Onboard 4in1 ESC MCU upgraded to EFM8BB21 Power supply: 2-4S LiPo/LiPo (7v/17v) Currents: 20A continuous 25A (5 seconds) Support BLHeliSuite programmable Factory firmware: 0.18.1Firmware target: F_H_40_48_v0.18.1 Default protocol: DSHOT150/DSHOT300/DSHOT600 Onboard UART ExpressLRS 2.4GHz Receiver Packet Rate option: 25Hz/50Hz/150Hz/250Hz/500Hz RF Frequency: 2.4GHzAntenna plug: IPEX Telemetry output Power:Less than 12dBm Receiver protocol: CRSF Default firmware version: ExpressLRS V3.0.1 Onboard voltage and Amperage meters settings Voltage meter scale setting 110 Amperage meter scale setting 470 Colour:Black Material:Composite Materials Package Contents: 1 x Flight Controller Kit(Due to different product batches, the appearance , which does not affect the use) 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.