70 mesh are used for extremely hard grinding, such as hard jade, alloy, ceramics, etc.
100 items are used for hard grinding, such as jade, glass, steel, resin, etc.
170 items is mostly used for grinding soft materials, such as gypsum, rubber, wood, etc.; also commonly used to trim 70 ground marks for later polishing.
320 items and 600 items are used to replace the relevant number of sandpaper, polishing special, can make the polishing cost greatly reduced at the same time, but also let the mechanic reduce the distress of early manual grinding.