The Starrett base extension has a 180mm or 260mm length and 17mm width, and is suitable for use with Starrett 3753 series electronic depth gauges (sold separately). The extension provides increased measurement capacity and is made of hardened steel for durability and accurate measurements. This base extension is suitable for precise measurement in a variety of manufacturing, machining, and mechanical engineering applications.

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.