... 3)with one steel coupling and one blue plastic cap 4)size:20mm,25mm,32mm,40mm,50mm BS4568 G.I Electrical Conduit ... ,electro-galvanized inside and outside surface,the thickness of zinc galvanized on the conduit surface is bigger or equal 14 micro meter2 ... ,25mm,32mm5)Material: Steel6)Package: bundle Hot dip galvanized steel class 3 and class 4