A slider lets you set a level of display detail in the exported viewer document between two extremes:

Less Detail (faster display)

Move the slider closer to this extreme for smaller exported file size with courser display granularity. Less detailed documents display more quickly and respond more quickly to view manipulations.

More Detail (slower display)

Move the slider closer to this extreme for larger exported file size with finer display granularity. More detailed documents display more slowly and respond more slowly to view manipulations.

It is possible to create viewer documents that are too large for your mobile device to display conveniently -- or possibly too large to display at all. If this happens, save the original model again with less detail.