A lengthwise section of a flexible drill rod, the section comprising - an outer tube, wherein - at least part of the outer tube is flexible in a transverse direction of the section and - the section is rigid to enable transmitting torque and thrust needed for drilling, the section further comprising - an internal pipe inside the outer tube for managing flushing medium flow through the section, the section comprising - a first connector arranged at a first end of the outer tube and the internal pipe, the first connector comprising at least one first connector element and at least one first pipe connector element, - a second connector arranged at a second end, opposite to said first end, of the outer tube and the internal pipe, the second connector comprising at least one second connector element and at least one second pipe connector element, - the first connector and the second connector being adapted to be connectable to each other so that the first connector is attachable to the second connector of another lengthwise section of the flexible drill rod, and the connector elements (9, 10) establishing - a tube connection for transmitting torque for rotation of said sections, and the pipe connector elements (17, 18) establishing - a pipe connection with an internal channel for allowing flushing medium flow in the internal pipe through said sections; characterized in that said at least one first connector element and said at least one second connector element establishing the tube connection are identical and comprise lengthwise directed extensions and gaps therebetween arranged around the connector (5, 6), the gap dimensioned for receiving the extension. - an outer tube, wherein - at least part of the outer tube is flexible in a transverse direction of the section and - the section is rigid to enable transmitting torque and thrust needed for drilling, the section further comprising - an internal pipe inside the outer tube for managing flushing medium flow through the section, the section comprising - a first connector arranged at a first end of the outer tube and the internal pipe, the first connector comprising at least one first connector element and at least one first pipe connector element, - a second connector arranged at a second end, opposite to said first end, of the outer tube and the internal pipe, the second connector comprising at least one second connector element and at least one second pipe connector element, - the first connector and the second connector being adapted to be connectable to each other so that - a first connector arranged at a first end of the outer tube and the internal pipe, the first connector comprising at least one first connector element and at least one first pipe connector element, - a second connector arranged at a second end, opposite to said first end, of the outer tube and the internal pipe, the second connector comprising at least one second connector element and at least one second pipe connector element, - the first connector and the second connector being adapted to be connectable to each other so that the first connector is attachable to the second connector of another lengthwise section of the flexible drill rod, and the connector elements (9, 10) establishing - a tube connection for transmitting torque for rotation of said sections, and - a tube connection for transmitting torque for rotation of said sections, and the pipe connector elements (17, 18) establishing - a pipe connection with an internal channel for allowing flushing medium flow in the internal pipe through said sections; - a pipe connection with an internal channel for allowing flushing medium flow in the internal pipe through said sections;