comes in a set of 3. The size is 
small- 30-40 mm
Medium- 40-50 mm
Large-50-60 mm
The Obsidian Yoni Egg is a powerful tool for strengthening the pelvic muscles while empowering the root chakra. Obsidian is a volcanic glass which is hard, smooth, and nonporous. Black Obsidian cleanses the root chakra as it aids with grounding and connecting to the Earth. This Yoni Egg is ideal for women who wish to appreciate the strength of their bodies and want assistance in remembering their purpose.