The Mitutoyo 500 series solar-powered Absolute Digimatic caliper is a digital caliper made of hardened stainless steel and uses Mitutoyo’s ABSOLUTE linear encoder technology. Hard-coated solar panels protect the solar cells storing energy for operation. These calipers can be used in any location, including dimly lit areas, and can be operated without replacing batteries. Although identical to dial and vernier calipers in their ability to make precise measurements, these digital solar calipers also have an LCD that displays in inch or metric units, increasing reading reliability. In environments with available light of 60 Lux or more, the caliper becomes active even it its uncharged state; it can immediately start measuring without zero resetting and operating speed is unrestricted. The 500 series solar-powered Absolute Digimatic Caliper has the ABSOLUTE electromagnetic induction linear encoder to help prevent overspeed errors. It measures outer diameter (OD), inner diameter (ID), depth, and step, where the butt end of the fixed jaw measures one end of a work piece before its upper/lower or inner/outer "steps" are measured. LCD resolution is 0.01 mm, repeatability is 0.0005”/0.01 mm, and accuracy is rated + or - 0.02 mm. A Digital LCD Data Reading Hold function is available with the optional Data Hold Unit (sold separately). An alarm alerts the user to low voltage, scale contamination, and counting value composition errors. A rolling thumbwheel makes fine adjustments and a thumbscrew locks the scale’s position. Response speed is unlimited. The caliper can be used continuously above 60 Lux ambient illumination. The built-in solar cells can store energy for up to three hours of caliper operation. The caliper can be used continuously above 60 Lux ambient illumination. Calipers measure the distance between two opposing sides of an object. They make inside, outside, depth, or step measurements, according to their type. Calipers are commonly used in architecture, metalworking, mechanical engineering, and machining. The simplest calipers have two legs to mark the two points and require a ruler to take the measurement. More complex calipers use two sets of jaws instead of legs and have up to two graduated scales. Vernier, dial, and digital calipers give direct and accurate readings and are functionally identical, having a calibrated scale with a fixed jaw, and another jaw with a movable pointer that slides along the scale. The vernier caliper has a scale sliding parallel to the main scale for an additional, fractional reading to improve measurement precision. The dial caliper has a circular dial with a pointer on a toothed gear rack replacing the second vernier scale. As with the vernier, this second measurement is added to the reading from the main scale to obtain the result. The digital caliper takes a differential by zeroing the display at any point along the slide, with an LCD that displays a single value in English and/or metric units. Mitutoyo manufactures precision measuring tools, metrology equipment, and systems. The company was founded in Tokyo in 1934 and formed Mitutoyo America Corporation in 1963, which is headquartered in Aurora, IL.