... . 3.DIN,SMS,ISO,IDF,AS,BS,BPE Standard. Sight glass (ISO9001:2008,CE,TUV certified) Specification: DN25-DN100,1"-4 ... : Mirror polishing(180G,240G,400G)Connection: welded , threaded , clamped and union type.Shape: straight type,cross type. Advantage: Prompt quotation, competitive ...