PixelsPerStud determines the density of pixels used for each world-space stud to render the contents of the SurfaceGui.

Higher values will cause the various GuiObject within to appear smaller if they are kept the same size. Conversely, lower values will cause objects to appear larger. However, if the GuiObjects are scaled proportionally (either by using a UIScale or modifying GuiObject/Size|Size or TextLabel/TextSize etc.), this property allows for higher definition to be used. It’s important to select a value based on how far away you expect a player to view the SurfaceGui. Be mindful that a large pixel density could negatively affect performance if the face of the adorned part is large enough.