T
he F4 line was invented by a guitar player. A friend complained that no one could make a guitar with a neck that stays straight. Intrigued by this problem, he realized that the harder you pull a string, the straighter it gets. To demonstrate this, pull on a guitar cord. If the guitar strings position the neck, rather than the neck trying to position the strings, then the neck stays straight. This is the key to the BORN TO ROCK concept (U.S. Patent 4,915,009).