New Tempest Air Filters

[Vansconvert]

I read the posts about the new tempest air filters as an alternative to the k&n filters.
Question - is the Tempest E-3260 round or oval? The reason I ask is that it has the same height as a k&n 3322 at 2.5 inches and the IDs are 5.25 and 5 respectively with the ODs at 6.25 and 6 and 3/8 respectively

 

[gasman]

It sure looks round..... https://www.aircraftspruce.com/catalog/eppages/tempest_airfilters_08-17579.php

 

[PilotjohnS]

Which one

There are two listed on aircraft spruce website. One for the o320 airbox and one for the io320/o360 airbox.

Which one do i need? I have factory io320 in rv9a. How can I tell which is the right one?