"直径21管螺纹螺距是多少"...直径21管螺纹螺距是多少
"管螺纹直径21是多少"...管螺纹直径21是多少
"21管螺纹尺寸"...21管螺纹尺寸
"外径21的管螺纹"...外径21的管螺纹
"管螺纹20"...管螺纹20
"螺纹直径21mm"...螺纹直径21mm
"外径21mm螺纹"...外径21mm螺纹
"20.5管螺纹"...20.5管螺纹
"管螺纹11g"...管螺纹11g
"外径21mm管螺纹"...外径21mm管螺纹
