Mack Tuff Dual Power Ring features 7 functions and 2 EZ Push-Button vibrating bullets. Ring is 100 percent silicone. Waterproof, Phthalates free, and RoHS Compliant. Sizes: Internal Ring Diameter - 3.5", Bullet Length - 2.75" each. Materials: Ring - Silicone, Bullets - ABS. 6 LR44 (AG13) batteries included