Drilling rod sub is used as a joint to connect the single drill rod, such as the internal threaded drill rod. It can be the joint tool for oil and natural gas, etc. It is made of hardened alloy. And all the materials should have excellent performance in tensile strength, yield strength, elongation and hardness. Its product should be in strict accordance with the standard of API Spec 7 and SY /T 5290-2000. The surface of the drilling rod sub is treated with phosphating and copper plating. With concern to its size and length, it varies from client to client.