Profile: Qingdao Donrex Co., Ltd. offers marine rigging hardware, sand casting, forgings, CNC machining, and metal stampings. Our threaded flange is made of ductile cast iron. It is widely used in power plants, industrial plants, water treatment units, plumbing, fire protection, mining & mine processing, oil field, and marine sectors. We offer electric and hydraulic winches, which are used in marine sectors.