4R Graduations read in 8ths, 16ths, 32nds, and 64ths of an inch Rigid rule is made from nonmagnetic tempered tool steel with a satin-chrome finish Industrial quality precision steel rule: 6" length x 3/4" width x 0.04" thickness Includes adjustable hook on end of rule 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. 4R Graduations read in 8ths, 16ths, 32nds, and 64ths 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.