Page History

...

For creative matching on AdX interstitial requests, FreeWheel DSP will match any creative that occupies 50%-100% of the screen width and 40%-100% of the screen height. This allows creatives smaller than the full screen size to match and be rendered in the center of the screen. This matching logic is exclusive to AdX and does not apply to other exchanges.

...

• Since responsive creatives can be rendered at different sizes, FreeWheel DSP will declare the size for AdX to render in the bid response. To fill the full screen, the size will be set to match the device's width and height.
• FreeWheel DSP will mark the creative as Responsive during the creative approval submission for AdX and in the bid response. This ensures that the creative is approved for bidding immediately for any responsively generated size.

...