Electric Guitar StringsWith the strength of an electric guitar string is defined as the thickness of a guitar string. It is generally used for steel strings. The dimensions in inches. The designation means 010 then e.g. 0.01 inches or 0.25 mm. The strength now to define an entire string set, usually the highest strength of the string is used. A 010-he is set for a guitar that is set in which has the high E string, the .010 and the other strings provide a matching strength.