It’s made from aisi4145h chrome-molybdenum steel. The content of microelement is effectively controlled. The surface of connector thread is phosphorized or copperized. There are three types according to its shapes and uses:

   a (same diameter): one sub only has one OD size

   b (different diameters): one sub has two OD sizes

   c (left-handed): sub’s connected thread is left-handed

Function: performing the function of connecting and switching in drills with different specifications

Feature: two types of subs, in accordance with the standard of SY5200－93 ( Sub of Drill Stem) or API  Spec7. The products for exfactory are tested by ultrasonic without damage and copperized on the surface of threads. We can produce all kinds of switchover joints with different specifications and lengthes.