Especially designed for the discriminating musician, the strings feature instant bow response, superior tuning stability and a soft feel to the left hand. The Peter Infeld violin strings mark an important chapter in Thomastik-Infeld's history. They are unlike any strings heard before! Creating unique sound colors is the essence of the Peter Infeld violin strings which are named to pay homage to Mr. Infeld who passed away in April 2009. The Peter Infeld strings, called "PI" for short, have the versatile ability to produce complex tones and unparalleled sound colors for the violinist and audience.