API Spec 7-1 AISI 4145h Water Well Drilling Drill Collar Lifting Sub 88.9mm- Nc35 Hebei Shitan Machinery Manufacturing Co., Ltd. API Spec 7-1 AISI 4145h Gas Drilling Lifting Sub 88.9mm- Nc35 Hebei Shitan Machinery Manufacturing Co., Ltd. API Spec 7-1 AISI 4145h Gas Drilling Drill Collar Lifting Sub 88.9mm- Nc35 Hebei Shitan Machinery Manufacturing Co., Ltd. API Spec 7-1 AISI 4145h Oil Drilling Lifting Sub 88.9mm- Nc35 Hebei Shitan Machinery Manufacturing Co., Ltd. API Spec 7-1 AISI 4145h Oil Drilling Drill Collar Lifting Sub 88.9mm- Nc35 Hebei Shitan Machinery Manufacturing Co., Ltd. API Spec 7-1 AISI 4145h Oil/Gas/Water Drilling Lifting Sub 88.9mm- Nc35 Hebei Shitan Machinery Manufacturing Co., Ltd. API Spec 7-1 AISI 4145h Oil/Gas/Water Drilling Drill Collar Lifting Sub 88.9mm- Nc35 Hebei Shitan Machinery Manufacturing Co., Ltd. API Spec 7-1 AISI 4145h Water Well Drilling Lifting Sub 88.9mm- Nc31 Hebei Shitan Machinery Manufacturing Co., Ltd. API Spec 7-1 AISI 4145h Water Well Drilling Drill Collar Lifting Sub 88.9mm- Nc31 Hebei Shitan Machinery Manufacturing Co., Ltd. API Spec 7-1 AISI 4145h Gas Drilling Lifting Sub 88.9mm- Nc31 Hebei Shitan Machinery Manufacturing Co., Ltd. 123>>>