... Ltd is one of the top level casing and tubing head manufacturers and suppliers,Website:http://www.zztopdownhole.com, with ... factory, we are able to produce API and oilfield casing head, tubing head, casing spool, tubing spool, tubing hanger, casing hanger, ... thread and locating mechanism. It is designed with various cable penetrating channels including pipeline channel for downhole safety valve control ...