The difference in appearance between UPN and UPE European standard channel steel In the construction, engineering, and manufacturing industries, European standard channel steel is often used, with UPN and UPE being common types. گەرچە ئۇلارنىڭ ئوخشاشلىقى بولسىمۇ ، ئەمما بەزى پەرقلەر بار ...
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