Length(s) of pipe mounted between the wireline [[blowout preventer]] and the [[stuffing box]] (or [[hydraulic packing head]]). Sometimes long enough to enclose the entire downhole instrument. Usually between 2 and 3 feet long. Should be equipped with 2 in. outlet through which the well can be killed or flowed if necessary. Under pressure, when broken [[cable]] strands bunch up under [[glands]] in the stuffing box, the blowout preventer can be closed and wires removed. If the downhole [[tool]] assembly is too long to fit inside a short (2-3 ft riser), the blowout preventer can be closed, the cable can be cut at a specific distance measured from the blowout preventer and a long riser with stuffing box installed. See illustration at [[lubricator]]. Also compare [[marine drilling riser]].