Can any one name this part? Cabin filter???.. pictures in car
 

https://cimg8.ibsrv.net/gimg/www.sco...cb1c65989.jpeg
https://cimg0.ibsrv.net/gimg/www.sco...0ea9e84f4.jpeg
https://cimg1.ibsrv.net/gimg/www.sco...b35d1230b.jpeg
https://cimg3.ibsrv.net/gimg/www.sco...edcdc71c6.jpeg
https://cimg5.ibsrv.net/gimg/www.sco...4f4fc3aa1.jpeg

It looks as if some of the late JDM SF5 models (2000-2002 C20 and T25) had special "blown" filters...........

https://ministrant-sponge.000webhost...20assembly.JPG

https://ministrant-sponge.000webhost...%20numbers.JPG

72830FC050 - Air piston assembly (complete with filter)
72821FC050 - Air Filter element

https://en.impex-jp.com/parts/new/se...tNo=72830FC050
https://en.impex-jp.com/parts/new/se...tNo=72821FC050

and there i was thinking I'd supplied enough info.................

72880 is just the PART CODE for this group of filters items across all Subaru models/variants. As is 72810 for the "air piston"

The specific part number (column 4) for JUST the filter (and you will need to order 2) for your forester is 72821FC050 as shown in the table below the diagram.
https://static.baza.farpost.ru/v/1456875231095_block
If you look at the way the part codes are linked on the diagram the filter "part code" 72880 is included with "part code" 72810 as a unit but also listed separately.

The link to IMPEX
https://ministrant-sponge.000webhost...X%20filter.JPG

I suspect your a/c will feel and smell fresher after you change those. Handy to use a/c for demisting this time of year....it's not all about cold air as such, just very dry air.