1.ISO9001:2008,CE,TUV certified. 2.DN25-DN100,1"-4".AISI304,AISI304L,AISI316,AISI316L. 3.DIN,SMS,ISO,IDF,AS,BS,BPE Standard. Sight glass (ISO9001:2008,CE,TUV certified) Specification: DN25-DN100,1"-4",large size to be customizedMaterials: AISI304,AISI304L,AISI316,AISI316LSurface treatment: Mirror polishing(180G,240G,400G)Connection: welded , threaded , clamped and union type.Shape: straight type, ...