X-Cut ia a good all purpose bur that can be used to section teeth and cut bone. Round tip burs are used to gain endodontic access, prepare cavities and mark cutting depth in crown prep, Pear Is used for root canal access and for undercutting dentin Cone Undercutting cavity preparation to create a mechanical interlock.' All burrs are in packs of 5..''NB: The larger the size number, the larger the burr.'''''