SPI 15-091-2 6.000" Grade AS-1 Steel NIST Cert Rectangle Gage Block
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The SPI 15-091-2 is a new individual rectangular steel gage block measuring exactly 6.000 inches, manufactured to Grade AS-1 per ASME B89.1.9-2023, which is the tightest tolerance grade in the American standard (equivalent to Grade 0 in older classifications), with flatness and parallelism verified at the factory. The block features two through-holes for wringing-rod use and for stacking in gage block sets, with lapped measuring faces ground and lapped to a mirror finish to allow wringing directly to other steel gage blocks without adhesive. Each block ships with an individual Certificate of Calibration traceable to NIST (NIST Test Number 685-O-0000034696-21, serial number F0251, deviation +14 millionths of an inch), inspected 2025-03-17 per the included certificate visible in the photos, and arrives in a fitted hardwood storage case with brass corner protectors and a latch closure.
Product Specifications
| Brand | SPI |
| MPN | 15-091-2 |
| Nominal Size | 6.000 in |
| Grade | AS-1 (ASME B89.1.9-2023) |
| Material | Steel |
| Block Shape | Rectangular |
| Calibration Standard | ASME B89.1.9-2023 |
| NIST Traceability | Yes — NIST Test # 685-O-0000034696-21 |
| Serial Number | F0251 |
| Deviation | +14 millionths of an inch (+0.000014 in) |
| Calibration Date | 2025-03-17 |
| Calibration Temperature | 68°F (20°C) |
| Through-Holes | 2 (wringing rod / stacking holes) |
| Storage Case | Fitted hardwood case with latch |
| Condition | New |