1.DBH MODULAR ROUGHING BORING HEAD 2.BE SUITABLE FOR SINGLE BIT BORING ,TWIN-BIT BORING AND STEP BORING WIHT WORKING DIAMETER FROM 25MM TO 122MM FOR MODULAR dck,120MM TO 90MM FOR MODULAR BST. 3.CAN BE EASILY ADJUSTED TO DIFFERENT BORING NEEDS FOR MACHINING ON DEMAND. 4.DBH MODULAR ROUGHING BORING HEAD 5.BE SUITABLE for rough boring 6.boring tool 7.rough and semi-finishing boring