Fill in the all the hollows (except screw holes) and cut the strips. I think it makes the harmonica sound better when properly set up. At least I can tell the difference. >>> ron >> >>Here's a look inside. Chris can explain. >> >>http://trinity.psnw.com/~dlmurray/gm.jpg >> Chris Michalek www.michalekstrone.com CD Available http://www.cdbaby.com/cd/michalekstrone