The basic structure of tungsten steel taps is an axially slotted external thread.In the cutting section of the tungsten steel tap relief grinding Angle 2 Ф, to make the cutting load distribution on several blade.
The old standard JB/T 4237-1992 corresponds to 00Cr19Ni10New STANDARD GB/T 20878-2007 Stainless steel and heat resistant steel grades and chemical composition
It means zipper with 2 way close end, with 2 slider&puller as below picture. Top/bottom puller can be different as requirements. The zipper teeth is shiny silver, with tape black, More colors, please contact us freely.