Crystal Bowl Singing Bowl I don't have expert knowledge, but here are my impressions. I hope they are helpful. Frequency measured by an app: 96Hz Impressions of the sound: It has a deep, resonant tone that resonates with the heart and calms the spirit. While the effect of relieving daily stress varies from person to person, it can be used as a good item for yoga, meditation, and purification. The inside is transparent, and the outside is matte. It's also attractive as an interior accent, such as a light cover or a goldfish bowl. Quartz Crucible Diameter: 45cm, Weight: about 10Kg - Shape: Cylindrical - Material: Quartz - Uses: Musical instrument (crystal bowl), meditation It's new, but I opened the bag to listen to the sound, so please refrain from purchasing if you are sensitive. Thank you for viewing.