Super Quality Raw Material --JUSTCUT's Corebits Using laser welded technology,improve the performance of segments,avoid segments off during drilling process. Machine --angle grinder (Pay Attention! If you drill through thick granite ,we recommend you to add enough water to help cooling the bits,which could prolong the lifetime) This corebit is extremely durable and is has high quality diamonds embeded within the segments and the side of the corebit to ensure you can drill through with ease.