Features Made of precision tool steel and ground on all 6 sides of the block. Cross drilling design allows efficient use of lower weight with maximum strength. Suitable for milling machines With wide applications, used for configuration, layout and inspection work. Precision and squaring on all sides within 0.0001 inch greatly improve work efficiency. The ultra-precise 1‑2‑3 block with screw key box is easy to use. Specification: Item Type: Ultra-precise block 1-2-3 Specification: Brand new Accuracy: 0.0001 inches. Quantity: 1 pair (2 pieces). Material: chrome-plated steel. Colour: silver. Size: approx. 13 x 21 x 4.5 cm/5.1 x 8.3 x 1.8 inches. Package list: 2 x Parallel Block 5 x screws. 1 x screwdriver. 1 x storage box Package List 2 x Parallel Block 5 x Screw 1 x Screwdriver 1 x Storage Box