Hexagonal Coupling Hexagonal coupling fixes the reamer connector and prevents overly tighten the threaded connection of connector and reamer Part number FORWARD HDD ng Size 03-01-011-21-0701 RX11×44 69 mm 03-01-022-21-0702 RX22×80/RX33×120/ RX40×160 89 mm 03-01-044-21-0702 RX44×160 113 mm