Convert from twain to zoll [Germany]

Unit Definition (twain)
The twain is an old word for the number two, derived from the Anglo-Saxon twegen. The American author Samuel Clemens (1835-1910), who had been a riverboat pilot on the Mississippi in his youth, took his literary name from a traditional riverboat phrase "mark twain", meaning "exactly two" fathoms of water. This was the minimum depth needed for the boats to operate safely without running aground.

Unit Definition (zoll [Germany])
The zoll ia a traditional German inch, equal to 1/12 fuss. Originally the zoll was equal to 1.037 inches (about 2.634 centimeters). There's no change in the plural.