1. Manually control: manually adjust X, Y, Z axis location as engraving starting point, manually open or close spindle, manully open or close cooling fan 2. File engraving: after off-line controller save file, it can connect the GRBL control board and process engraving, no need to connect PC computer 3. Save file: after the off-line controller connect PC, it be recognized as USB, large capacity storage device, can access engraving file directly. Note:Please do not connect the offline controller and the PC together, otherwise the PC can not work for the laser burner. And the actual capacity of TF memory cars is around 960 MB. Due to different product batches, the appearance , which does not affect the use. Colour:As Shown Material:Plastic Package Contents: 1 x GRBL off-line controller 1 x Extension Cable 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.