Grain
types:
aluminum oxide (A/O): standard grade
for most usages
zirconium oxide (Z/O): tougher grain
for coarse grade usages
silicon carbide (S/C): special applications
ceramic alumina (C/A): special applications
Backing
types - Belts:
Cloth - (X)
standard stiff, (J) flexible, (Y) very stiff, & (JF) very flexible
Paper - (F)
standard very stiff