We customize non-standard hollow double end screws, stainless steel extended hollow bolts, long oil injection screws and lengthened connecting extension rods. Made of high-quality stainless steel and carbon steel, processed by CNC precision machining and cold heading forming, with smooth inner and outer holes, precise thread and stable overall structure. Hollow through-hole design realizes oil injection, ventilation and line threading functions; extended integral structure is used for connection lengthening and pipeline extension. All specifications, hole diameter, length and thread type can be customized according to drawings and samples. Support small batch proofing and mass wholesale, widely used in mechanical lubrication, equipment connection, pipeline assembly and industrial matching.