B & W 801 S3 bass alignment filter

Is there a difference between bass alignment filters for 801 S2 and 801 S3 and how to spot the difference. Will 801S2 filter work with 801 S3?. Thanks
Just to be more specific, I am interested in differences, if any, for B & W made filters.
Someone posting on your last thread about 801s owned several different bass alignment filters. Read through your last thread to find him and send him a message.

I would go with the B&W bass alignment filter because I am a stickler for wanting to hear it the way the engineers intended it to be.