Mack Tuff Power Ring features 7 functions and an EZ push button vibrating bullet. Ring is 100 percent silicone. Waterproof, phthalates free, and RoHS compliant. Sizes internal ring diameter 3.5 inches, bullet vibrator length 2.75 inches. Materials Ring Silicone, Bullet Vibrator ABS plastic. 3 LR44/AG13 batteries included.