Go to the site and get the one Ekam quoted;
http://e-partssales.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=P&Category_Code=986maint
This is a charcoal filter, good for keeping out the fart smells. It always amuses me to think this car has a cabin filter, it a convertible and I always ride with the top down. Now my Lexus, I can understand a fart filter when I'm driving that.