Two 1.85" (4.7 cm) hand-blown solid glass balls with removable silicone strap. 4.25 insertable inches (10.8 cm). Glass balls weigh .5 lbs., so they can be felt inside. Sturdy pull ring. Run under hot or cold water for different sensations. Sterilize by placing in boiling water or on top rack of dishwasher. Waterproof and Phthalate free.