... ,T45,T51, Length:1000mm-6100mm extension rods,driftiing rods BETOPPER Drifting Drill Rod/Extension Drill Rod Extension rods are made by hollow drill ... steels, there are two shapes of extension rods, round type and hexagonal type,This hollow hole are ... be used for connecting coupling sleeves, shanks or bitsUsually for extension rods, there are R22,R25,R28,R32,R38,T38,T45 ...