GRBL1.1f firmware enables offline tool setting and engraving, letting users complete projects without constant computer connection for flexible workflow. Adjustable power settings from 0 to allow precise control of spindle speed for different materials, ensuring optimal engraving results up to 20000rpm. Over-current and short-circuit protection rated at 2A safeguards the board and connected devices during intensive engraving tasks. Aluminum alloy heat dissipation and stepper motor drive support simultaneous offline module and computer connection, streamlining CNC project management. Optocoupler isolation reduces heat generation, while linear spindle speed adjustment and USB interface compatibility provide precise control for accurate engraving. Voltage: 12-24 Color: As shown Material: Metal Package Contents: 1*pcs cnc controller 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.