Granite Square Rules

Granite Square Rules Grade 00
size : 160 x 160 mm  Resolution : 2 um
        200 x 200 mm  Resolution : 2 um
        250 x 250 mm. Resolution : 2.2 um
        315 x 315 mm. Resolution : 2.6 um
        400 x 400 mm. Resolution : 3 um
        500 x 500 mm. Resolution : 3.5 um
On inspection of verticality and parallelism as well as absolute 90 degee measuring.