Tolerance of planeness: Standard
JB/T7975-1999
Grade 000 = 1 × ( 1+d/1000 ) μm
Grade 00 = 2 × ( 1+d/1000 ) μm
Grade 0 = 4 × ( 1+d/1000 ) μm
Grade 1 = 8 × ( 1+d/1000 ) μm
( "d" is the diagonal mm ) (The measuring temperature is normally 20±2°C )

Granite measuring tools characteristics

he product was sold to japan with the Mitutoyo standard

1.    high precision reliable stability resistance to deform and guaranteed accuracy under normal ambient temperature.

2.     No-rust and anticorrosion

3.    wear resistance long service life

4.   any working surface cutting or scratching dose not bring about rough “edges”which  might influence its measuring presicion.

5.   nonmagnetization.

6.  gloosy surface without sluggishness when the workplaces or tools are moving on it

7.  It may chip, but will not develop a burr.  It is easy to keep clean.