1. With BOOT and RESET buttons reserved, users can update the firmware via DFU mode by USB. 2. Added protection circuit on the thermistor avoids burning the main control chip caused by leakage current from the heating rod. 3. Connect the USB witha jumper cap to get it power on, which effectively isolates the main control board DC-DC from USB 5V. 4. Reserved I2C interface allows for filament broke and clogged detection, and supports other DIY functions. 5. Added anti-flyback diodes on the heating rod and fans' ports effectively protect the MOS tube from being burned due to reverse voltage. 6. Anti-reverse connection protection on the power interface prevents users from burning the motherboard when mistakenly connecting the reverse power line during DIY. External Dimensions: 40mmx 40mm Installation Dimensions:Hole spacing 31mmx 31mm, M3 screw holex 4 Microprocessor: ARM Cortex-M0 STM32F072C8T6 48MHz Input Voltage: DC12V-DC24V 9A Logic Voltage: DC 3.3V Heating Interface: Heating Rod (E0), maximum output current: 5A Onboard Sensor: ADXL345 Colour:As shown Material:PCB sytle:EBB42 / EBB36 Due to different batches, there may be differences in product appearance and printed text, which will not affect use<br><br>Package Contents: 1 * Extruder Breakout Board 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.