The SPI 17-831-9 is a new caliper-type inside micrometer with a measuring range of 5–30 mm and a graduation (resolution) of 0.01 mm, as confirmed by the product label, the engraved scale markings on the instrument, and the barcode label reading "INSIDE MIC,5-30 MM,0.01MM." Unlike tubular or telescoping bore gauges, caliper-type inside micrometers use a direct-reading micrometer barrel with spring-loaded, jaw-style measuring contacts, providing fast and repeatable bore measurement without the need for extension rods in the specified range. The instrument ships complete with a spanner wrench for thimble adjustment, a calibration ring gauge (setting standard) stamped with a reference number, and a fitted hardwood storage case with foam insert — confirming this is a full kit. SPI (Swiss Precision Instruments) is an ANSI/ISO-recognized metrology brand; the wooden case lid bears an SPI "Certified" seal, indicating the gauge ships with a certificate of inspection. Typical applications include measuring small bores, grooves, and internal diameters in precision machining, tool-and-die, and quality-control environments.