The recommended eggs to use are made of jade. Jade and obsidian eggs can be drilled to accommodate a string passed through their centers for the advanced weight lifting practice. The obsidian eggs may require a diamond drill bit. It is recommended that any egg should be drilled, even if weights are not used. The string may help in removing the egg. Jade eggs are preferable because they are sturdy. smooth and non-porous. You may also find that jade eggs are far less expensive. These eggs are available through the Universal Tao. The use of a stone egg to strengthen the vagina is a practice which evolved in ancient China. As time went on, the secret of this practice remained in the Royal Palace and was taught only to the queen and concubines. Many who mastered the technique experienced very good health, remaining young and bountiful, with sexual organs in old age as tight and resilient as those of a young, unmarried lady. Originally, however the Egg Exercise and Vaginal Weight Lifting were implemented for improving health, both physically and spiritually, since these exercises provide more power to the Chi Muscle to lift the sexual energy inward and upward where it will be transformed into higher spiritual energy. The egg is a marvelous way to strengthen and control the Chi Muscle. It is easier to practice control of this muscle with an egg in the vagina since, as the egg moves, you can feel the direction in which the Chi Muscle moves more distinctly. Controlling this voluntary muscle means control of the many involuntary muscles in this area as well. Also, as you master the use of this muscle of the vagina and perineum, you simultaneously tone up the lower abdomen. Thus, your performance of Ovarian Breathing, the Orgasmic Draw, and the Organs’ Orgasm greatly improves, and the flow of sexual hormones increases.