The vibrating plug "Hulk" by Colt is made of silicone. The firm shaft with smooth tapered head for easy entrance finds its extension in a safety ring and a ribbed handle. The Hulk is a downright monster with ten functions of intense vibration, escalation and pulsation which can be adjusted to four different speeds each with the LED-illuminated easy touch controller. This vibrating plug is waterproof and can be used while taking a shower. The vibrating plug Hulk is the perfect toy for anyone who praises quality and durability. Requires 4 AAA batteries.