... dual tube drilling rod for air reverse circulation (RC) drilling in mining exploration purpose, OD.102MM, 108MM ... , 114MM, Premium drilling rod for air reverse circulation (RC) drilling in mining exploration driling.O.D. Available: ... 89mm, 102mm,108mm,114mm (3-1/2", 4", 4-1/4", 4-1/ ... 2")Length: 1.5mm, 3.0mm, 6.0mmThread: Matrix, Metzke double tube drilling ...