The 640JZ model has a simple one-button design to take accurate measurements. The 640RJZ model has reverse movement (no button) and can be operated with one hand for ease of use. Starrett No. 644-441 Dial Depth Gage .001 Graduation 1.000 Range W... 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. 450-12 Starrett Dial Depth Gage: 0-12 - Call 800-469-0132 or Buy Online Buy Dorman 604-147 HVAC Blend Door Actuator for Specific Buick / Pontiac Models ... Models Fits select: 2000-2005 BUICK LESABRE, 2000-2005 PONTIAC BONNEVILLE The dial face has distinct, easy to read figures. Depth gauges are typically used in manufacturing, machining, and mechanical engineering. Contact Case Starrett Dial Depth Gage, 0-1/2", EDP 52705 - 640JZ - Penn Tire Tread Depth Gauge These gauges come in a fitted case. Made For You - It offers everything you need, including a broad line of each indicator type, an extensive range of accessories to configure and position the gage, and as needed, an indicator-based, custom engineered solution. The Standard for Excellence - Proudly made in the USA, Starrett combines over 140 years of American heritage and innovation with globally sourced materials to deliver exceptional quality tools and products. This provides stability and accuracy when taking measurements. 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. Electronic indicators are sold separately. The Starrett 640 Series Dial Depth Gauges, Indicator Type, Inch, have a measurement range of 0 to 0.5, a resolution (or smallest graduation interval) of 0.0005, with + or - 1 graduation (0.0005) for the first 2.5 revolutions of accuracy. The company, founded in 1880, is headquartered in Athol, MA. Depth gauges are precision measuring instruments used to determine the depth of any shape that has a step, groove, or slot. Each type has its own unique strengths.