These Replacement Glass Beds for Creality Ender 3 printers are stocked to be used as printing surfaces on top of Heatbeds, and have been carefully sourced for their impressive flatness tolerance.
Compared to many other panes of glass that are available from various other outlets, these have been manufactured specifically to meet excellent tolerance standards, which is what makes these glass beds so effective as print surfaces for 3D Printing.
With an unstable or imperfect print surface, there may be times in which your 3D Filament doesn't stick to or form on the bed properly.
This is commonly due to a print surface that is not completely flat, in which case the filament may not always be the same distance from the bed.
With a perfectly flat surface, however, your extruder will always be the exact same distance from the bed, regardless of what point on the bed it is printing, resulting in better quality and consistency for your first layer and in turn improving the overall quality of your prints.