Bivert modules are used to increase contrast and the chromaticity of your display. You can currently install a bivert module in your Game Boy DMG or Game Boy Pocket (MGB).
Using a hex inverted, these modules switch the orientation of pixels. What once was dark becomes light and vise versa. Many modders will not go without one of these modules are they are an easy and noticeable gaming improvement for the Game Boy DMG and Game Boy Pocket.