Product Description ¯¯¯¯¯¯¯¯¯¯ Obsidian (Black Obsidian) ・12mm ・Inner diameter 17cm ・When you're feeling negative and need motivation. ・When you want to overcome difficulties and grow. ・When you want to eliminate distractions and have the focus to persevere. Origin ¯¯¯¯¯¯¯¯¯¯ ・USA, Japan, Canada