What Is the Difference Between Flex and Fixed Size Ad Slot?

Learn more about Flex and Fixed-size ad slots here

All Social Display creatives are trafficked and tracked in your DSP as display tags.

Nova ad tags are targeted to IAB standard display sizes (300x250, 300x600, 320x480 and 336x280).

Flex (Full Sized) Ad Slot

Nova social display ads are responsive
The ads will be rendered as flex (full-sized) size by default and automatically resize the ad slot's iframe.
If trafficked to a standard 300x250, 300x600, 320x480 and 336x280 ad slot, the slot automatically resizes and loads the Flex size
As a result, they appear much larger than the standard display ad size and deliver better creative performance when Flex size is used.
Nova tag dynamically checks to see if the ad slot is non-resizable (also known as Cross-domain/hostile iframe). If so, it falls back to its fixed-sized version
A separate tag does not need to be trafficked as this happens automatically

Caution: There could be an instance where our ad tag is resizing as Flex but the Parent DIV (HTML Element) is not letting the ad resize and cutting the ad preview, in such a case, you should Blacklist such domain.

We recommend the following exchanges for optimizing for Flexible Inventory:
- Pubmatic
- OpenX
- Index Exchange
- AppNexus
- Magnite
- Bidswitch.
  
  There are certainly more and other exchanges you can use, these have simply been reported as the best performing!

Note: The reason you see the 300x250, 300x600, 320x480 and/or 336x280 previews in our dashboard is to ensure that you are able to see how the ad will render in case it hits a site that does not allow resizing and loads our fixed-size

All social display creatives will automatically render the fixed-size fallback template when served to an un-resizable hostile iframe.

Fixed Ad Slot

These ads remain a specific size (like 300x250, 300x600, 320x480 or 336x280) and do not resize automatically
About 10% of sites in the open web load ads in Safe-frames or Cross-domain (a.k.a hostile) iframe

There are 3 instances where fixed-sized ads automatically load

When the ad is trafficked to safe-frames, e.g. GAM SSP (Google Adx supply).
When the ad is trafficked to App inventory
When the ad lands on an AMP site (very rare).

In general, to reduce fixed-sized rendering percentage and ensure good performance we recommend blacklisting the following domains:

High Probability of IVT (invalid traffic) and BOT clicks for fixed sized rendering

Apart from performance another drawback of fixed sized rendering is the high probability of MOAT and DSP marking it as Invalid Traffic (IVT) and the increased possibility of BOT attacks/clicks.

Cross-domain (a.k.a. hostile) iFrames limit what MOAT tag can measure. If a Moat tag loads in a hostile iFrame, their geometric approach — which measures pixel percentages and relative placements to report viewability does not work. As a result MOAT marks that traffic as unmeasurable or IVT. This is also true for Nova's internal viewability measurement.

When Nova ads land on cross-domain iframes and/or Safe-frames it is unable to resize the iframe and as a result fall back to loading the fixed sized design. Therefore, if the percentage of fixed sized rendering is high, it is an indicator that there is a high probability that the creatives in the campaign are landing on cross-domain (hostile) iframes.

BOTs crawl on the page looking for standard IAB sizes (Fixed sizes) to attack and fire fraudulent clicks. With our flex rendering, we resize the ad slot to non-standard sizes after our tag lands on the page. This in turn reduces the possibility of Nova Flex ads being attacked by BOTs.

Rendering options

Flex
Fixed 300x250
Fixed 336x280
Fixed 300x600
Fixed 320x480