Rated 5 mice by MacUser (on-line review as ConvertUnits Pro, May 1997)
MetricMaster is a measurement unit conversions calculator for the Macintosh, containing many hundreds of metric/S.I., imperial, U.S., and other units in its database, most to 14 significant digit precision. New units can be added and unwanted ones removed. Supports ft/in/fractions, different number formats including scientific notation, and complete control of significant digits. Can also convert currencies, clock times, and many physical constants. On-line info is available on the history and development of modern measurement systems.