Unlimited 20 mm Crystal Tuning Forks - A440 Hz - Includes 1 Crystal Tuning Fork/Great for Sound Healing & Sound Therapy

Tuning Fork,Mallet Steel Guitar Tuner 440hz Tuning Fork Musical Instrument Violin Metal A440 Tuner Musicians Tuning Forks

“Countries, and even cities, each set their own criterion, with the result that tuning varied widely from one locale to another”: How 440Hz became the “concert pitch” – and the argument to change it to 432Hz