6 inch rigid steel rule can be used to measure or as a straight edge. Place the hook perpendicular to the edge of the rule at the 0 in mark, and bring it against the edge of your workpiece; the hook will register zero, even if the edge is rounded or chamfered. Nonmagnetic tempered tool steel will not attract metal shavings. Satin chrome finish with easy-to-read high-contrast black graduations. 16R Graduations read in 32nds, 64ths, 50ths, and 100ths of an inch. Industrial quality precision steel rule. 6 inches long x 3/4 inch wide x 0.04 inch thick. For over 60 years, SPI has introduced innovative products to the metalworking and laboratory industries. SPI measuring instruments are durable, precise, and reliable — all backed by an industry-leading 2-year warranty.