Product review (5 stars): Charcoal Filter INSERTS
What you get: 2 x charcoal filter inserts, 4 x clips, instruction sheet complete with photographs.  These charcoal filter sheets DO NOT replace the plain metal filters.  These clip on to your existing filters to add an additional filtering/odor reducing layer.  They clip on to your filters with the included clips (2 per filter) and it is easy to follow along with the included instructions.  NOTE: if you want to replace your plain metal filters you will need to order a different item -- I can't help you there because I just clean them (the original NON CHARCOAL filters) with engine cleaner, soaking in soapy water, and then copious rinsing.