Manufacturer: Microplan   Model: Black Granite Accessories     Linear Rules   For high precision testing of linearity, for comparing guides or lapped surfaces. The lapped surface is available in three levels of precision (grade 1, 0, 00).     Level Parallel Rules   Manufactured in two H-shaped lapped parallel surfaces to ensure stability and ligthweight. The lapped surface is available in three levels of precision (grade 1, 0, 00). The parallelism tolerance is equal to the flatness.     Squares   Perfect for perpendicularity testing, these set squares are extremely reliable for due to their limited tolerances and stability of the base. Holes are placed in the larger versions to reduce weight and for shipment. The tolerance of the lateral faces is +/- 0.2mm. Nine versions are available from 200 x 150 x 30mm up to 1500 x 1000 x 160mm.     Right-Angled Plates   These comprise three perpendicular lapped plates with one-side face having threaded tapped inserts (holes) for attaching the tested article. Five versions are available from 150 x 150 x 100mm up to 500 x 500 x 220mm.     Cubes   Manufactured in either two, four or six lapped, plane and parallel surfaces. Four versions are available from 50 side up to 200 side.     "V" Prisms 90 degrees   Ideal for testing cylinders. Three versions are available, 100 x 70 x 50mm, 140 x 100 x 60mm and 200 x140 x 70mm.     Parallel Piped for right-angle testing   Its square form ensures greater stability. Three faces lapped perpendicular to each other and the upper base. Three adjustable feet are fitted to the lateral face. It is suitable for square testing on measuring instruments and machine tools. Five versions are available from 250 x 250 x 40mm up to 1000 x 1000 x 80mm.     Cylinders   These granite cylinders are manufactured with two support surfaces which are perpendicular to the cylindrical surface. Suitable for for squareness testing, these cylinders have reduced tolernaces on both straightness as well as on cylindrical. Four versions are available from 70 mm up to120mm diameter.