This is the designation for the “hardness” of the attachments. The globally accepted marking of nozzles, depending on the size of the grain of the diamond nozzles or the tooth of hard-alloy in its working part (graininess, roughness, hardness, “anger”) is as follows:
| yellow stripe | i | minimum | superfine grain |
| red stripe | f | fine | fine grain |
| blue stripe | m | medium | medium grain |
| green stripe | c | coarse | coarse grain |
| black stripe | s | supper | very coarse grain |
| two black stripes | e | extra coarse | super coarse grain |