Visual Electronic Device for Easier bed leveling: it's a gadget that most too can do without for your FDM printer: this, keep from paper, this allows you to not have to update or change firmware to make use of this in most cases, create a nearly perfect leveled buildplate.How to use it: Put the board and under the nozzle in the middle of the bed, Move the Z down, progressively smaller steps, until the light just starts to flicker; Disable your steppers, Move to each corner and adjust until the light just flickers, Repeat the corner adjustments 2 to 4 until all are set to just flicker without adjustment; Do a Z offset wizard and verify the default, You're done.What it does not do - general 5.7-5.8mm offset. Does not "preset" your z-offset while leveling your plate. you will still need to the proper z-offset in the printer .size: 9.30 x 4.29 x 2.21 cmMaterial: Plasticcolour: greenPackage Contents:1 x Bed Sensor LevelingOnly 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.