Strings (tennis)
The material used in tennis string can significantly affect a player's performance, and even health. Several materials are used to make tennis strings. They vary in terms of elasticity, durability, rebound efficiency, tension holding capability, and manufacturing cost, among other considerations.
Twelve-string guitar
Some performers use open tunings and other non-standard guitar tunings on 12-string guitars. Some performers have experimented with tuning the two strings within a course to intervals other than octaves or unisons: jazz guitarists such as Ralph Towner (of Oregon), Larry Coryell, and Philip Catherine have tuned the bass courses of their 12-string guitars to the upper fifths and trebles to the lower fourths instead of octaves and unisons; Michael Gulezian tuned strings in the top two courses to whole-tone intervals (and possibly some of the other strings an octave lower) to achieve a very rich, complex sound. The greater number of strings offers almost endless possibilities.