Violin construction and mechanics four open strings, usually tuned to G, D, A, and E. The strings run from a tailpiece attached to the base, across a wooden bridge, continue towards the neck of the instrument running parallel to the fingerboard, and connect to the pegbox located at the very top of the violin. They are wound around four tuning pegs that are mounted sideways through holes in the pegbox. The bridge helps to hold the strings in place, while the pegs maintain the tension necessary to produce vibration. Strings were first made of sheep's intestines (called "catgut"), stretched, dried and twisted. Contrary to
Strings (tennis) or more of stringbed stiffness. However, many players who hit the ball hard enough to break the strings simply restring rackets whenever the strings break. The United States Racquet Stringers Association (USRSA) offers two levels of certification for stringers: the Certified Stringer and the Master Racquet Technician, of which around 350 exist worldwide. The Master Racquet Technician certification process includes testing of the stringer's ability to string a racquet, perform grip work, identify mistakes in an improperly strung racquet, and pass a written test that covers not only strings, but racquet technology as well. Since 2004, "RSi," the USRSA's monthly