The water containment suction ring is used to hold water whiling drilling holes on granite, marble, and other high gloss surfaces. Water will act as cooling and lubricating agent when drilling with diamond core bits, thus increase the speed of drill as well as life of the bits The set comes with a water ring of 3" in inner diameter for diamond core bits of up to 3", and a 1-1/2" in inner diameter for diamond core drilling of up to 1-1/2".