The Best Of Macho Ultra Erection Keeper Blue Vibrating Ring with Dangling Balls features 9 functions. Keeps you hard. Super stretchy. Dangling balls. Increased pleasure for him and her. Waterproof vibrations. Phthalate free. RoHS Compliant materials cock ring sleeve SEBS silicone. Bullet vibrator ABS plastic. balls metal. Size overall length 4.25 inches. inner ring diameter 1.125 inches. Vibrating cock ring requires 2 AG10/LR1130 batteries. included.