This mute was invented for and used by Jasha Heifetz. The first prototype was developed in 1947. In 1968 the mute molds were lost and the mute was not made for over a decade. Finally a modified Heifetz mute was reintroduced in 1989: What makes this mute special is that it can be placed between any 2 strings achieving different sound effects as needed. Also, this mute reaches all the way down the bridge creating the perfect mute-effect. The rubber mute is held together by 1040 spring feet cut at 0.75 cm, bent and heated, then tempered in 140 degrees. This mute was created for future generations of violinists to enjoy.