The ground surface on the GG is often referred to as, 'the tooth.'

3-M, 'Scotch Magic Tape' has a tooth:
http://blog.baquephoto.com/wp-conten...tapefocus1.jpg
http://www.flickr.com/photos/midnigh...n/photostream/
http://www.flickr.com/photos/midnigh...n/photostream/

Slightly milky, Vinyl page protectors/document sleeves have a tooth:
http://salihonbashome.blogspot.com/2...und-glass.html