Type(mm)	Perpendicularity between adjacent measuring surface			Flatness and straightness of measuring surface			Flatness and straightness of datum surface
	Precision Grade (μm)
	1	2	3	1	2	3	1	2	3
200 × 200	8	16	30	4	8	16	6	12	24
300 × 200	10	20	40	5	10	20	8	16	30
300 × 300	10	20	40	5	10	20	8	16	30
400 × 300	12	24	45	6	12	24	10	20	40
400 × 400	12	24	45	6	12	24	10	20	40
500 × 400		28	50		14	28		24	48
500 × 500		28	50		14	28		24	48
800 × 600		35	60		18	35		28	55

Used to test the perpendicularity and parallelism, and can be used as verfication standard of 90 degrees .
Larger size or special design can be customized.