Screw the fixing ring nuts back on.

拧紧背面的固定环型螺帽。

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Cone head drive screw with washer - used on roof for keeping fixing holes watertight.

锥头机螺钉垫圈-用于屋顶保持固定孔水密。

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Fixing mode: it is fixed by means of concealed screw and shaped part.

固定方式：采用暗式螺钉和异形件方式固定。

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