Universal square box with reasonable design, stable structure, high precision, wear-resistant, long life and so is widely used in machining, tool shop, assembly shop, machine check) repair shop, measuring rooms and precision machining test, measurement and grinding. our standards will be flat square box is divided into six, namely 000,00,1,2,3 level, the accuracy is roughly corresponding to the GB1184-80 provides the flatness tolerance of 1,2,3,5,7, 9 6 grades. View of the 000 flat no sale of goods, order accuracy of the tablet is divided into five levels, namely, 00,0,1,2,3 level. 
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