Crystal Vibes Frosted Crystal Singing Bowls are very smooth and thick for a more relaxing and clear tone. They are made from quartz crystal and are fired at extreme temperatures until they fuze creating the a quartz glass. Each bowl comes with an o-ring and suede striker and is clearly labeled with the note it is designed to hit on the interior. Even with the varying sizes of the bowls, each bowl contains a variety of possible notes. www.universalcompanies.com