Yoni is the Sanskrit word which refers to the vagina or womb. Loosely translated it means "sacred place," "sacred temple," or "source, origin." It is used to describe the sacred source of life; the Universal Womb

There are several physical & spiritual benefits to a regular yoni egg practice.

Physical:
-Strengthening, tightening, & toning of the muscles of the vagina, uterus, and pelvic floor (think supercharged kegels! Your own vagina gym)
-Learning to actively use vaginal muscles for pleasure, childbirth, postpartum & other reproductive healing.
-Shrinking fibroids & cysts, reversing weak bladder and uterine prolapse
-Hormone regulation
-Increased lubrication, libido, elasticity, vaginal muscle manipulation, & orgasm expansion
-Detoxifies the uterus/womb
-Helps with fertility
-Helps reduce menstrual cramps & pelvic pain

Spiritual:
-Healing from past trauma ("trauma" is not exclusive to abuse but also negative energy stored in the womb)
-Increased deep connection with self, increased awareness & intuition -Emotional & chakra balancing
-Explosion in self care practices & creative power
-Cultivating & protecting Magic
-Auric cleansing
-Meditation aid
-Channeling and divination

Keep in mind additional metaphysical properties will differ with each crystal/stone type.

Jasper is excellent for creative flow as it clears deep unwanted emotional blocks. Helps one to become more adventurous. Stimulates Life Force flow and natural rhythms.

~Yoni Egg Quick Size Guide~
Large: BEGINNING GODDESS
Medium: INTERMEDIATE
Small: ADVANCED
"
Source: http://www.nirvanawild.com/product/wine-jasper-yoni-eggs-large
Source: https://www.instagram.com/p/BPaZ_oZDeM1/?hl=en