One single resonant tone. Tuned to the frequency of a Platonic Year using the calculations of Hans Cousto. The Meinl Planetary Tuned Platonic Year Tuning Fork is tuned to precisely deliver a F3 note at a frequency of 172.06 Hz. According to Hans Cousto this is the frequency which matches a Platonic Year. The Meinl Tuning Fork is designed for therapeutic use.
