Viewability 100% is calculated as Viewable-CPM and you will only pay for banners that are defined according to the IAB standard:
minimum 50% of the banners pixels are shown for at least 1 second.

Formats
930×180
160×600
320×160 / 320×320
Viewability 100% is calculated as Viewable-CPM and you will only pay for banners that are defined according to the IAB standard:
minimum 50% of the banners pixels are shown for at least 1 second.
Formats
930×180
160×600
320×160 / 320×320