Starrett 440Z-3RL Vernier Depth Gauge, Ratchet Stop, Lock Nut, Micrometer Type, 0-3" Range, 0.001" Graduation, 2.5" Base, 3 Rods, +/-0.0001" Accuracy

The Starrett 440, 445 Vernier Depth Gauges, Ratchet Stop, Lock Nut, Micrometer Type, Inch, depending on the model, have a measurement range of 0 to 3", 0 to 6", 0 to 9", or 0 to 12"; a resolution (or smallest graduation interval) of 0.001"; with + or – 0.0001" of accuracy. The vernier scale enables precise measurements in fine units. These gauges include 1/8" diameter measuring rods to cover the intended range. The bases are available in a choice of 2.5", 3", 4", or 6" long, and all measuring surfaces of these units are hardened, ground, and lapped for durability and accuracy. These gauges have a ring-type knurled lock nut, ratchet, and speeder for stability and to apply uniform pressure and make quick adjustments for precise measurements. These units include a protective case. Depth gauges are typically used in manufacturing, machining, and mechanical engineering.

Depth gauges are precision measuring instruments used to determine the depth of any shape that has a step, groove, or slot. These gauges often take the form of sliders that travel on a measuring beam or rods, are moved to position by hand, and then adjusted with a calibrated screw. The base of the gauge rests at the top of the shape whose recession is to be measured, while the beam or rods extend to the bottom of the recession to determine the measurement. Gauge position is read from a graduated scale, dial, counters, or an electronic display.

The L.S. Starrett Company manufactures precision measuring tools, metrology and testing equipment, and saw blade products. The company, founded in 1880, is headquartered in Athol, MA.