Hartz - H-Chew-O Drops Large This toy can be filled with water and frozen for a refreshing chewing experience When your dog chews on the rubber, ice-cold water trickles through the micro-holes on the ball The toy is made from durable rubber so it's strong and lasts long And the tight rubber cap increases the toy's safety and makes it easy to fill the cavity with water by removing the cap with pliers a great summer toy, but a terrific outdoor and fetch toy.