现货供应偏梯形螺纹消失量规/消失规

http://www.szfyou.cn 偏梯形螺纹消失量规 用来检验消失螺纹根部以保证外螺纹有足够的长度并且确为接近消失点螺纹 Measuring the condition of buttresds-casing thread to make sure enough length of external thread and knowing that the thread is the thread vanishing point