32-Piece Grade 0 Gauge Block Set Includes precision slip gauge blocks for accurate calibration and inspection, ranging from small to large sizes. Grade 0 Accuracy for Metrology Applications Manufactured to ISO 3650 standards with ultra-tight tolerances, for high-precision labs and tool calibration. Hardened Steel Construction Made from wear-resistant alloy steel for excellent durability and long-term dimensional stability. Mirror-Lapped Surface Finish Each block is polished to a mirror finish for superior wringing performance and minimal measurement deviation. Protective Storage Case Included Comes in a secure wooden case for organized storage and safe transport, for toolrooms and inspection setups., Manufacturer: SOYWIM