Valve manufacturer Ductile Cast Iron Knife Gate Valves have two types: NRS (Non-Rising Stem) and OS&Y (Outside Stem and Yoke). Description Size: DN50-600 Class: PN6/PN10/PN16 Test: EN12266 Flange: EN1092-2/ISO7005-2 Operation: Handwheel/Extension/Gearbox Material List No.PartMaterial 1U SeatEPDM/NBRD 2BodyDuctile Iron 3KnifeSS304/316 4StemSS420/304 5CoverDuctile Iron 6Seal NutBrassValve manufacturer website:http://www.thitco.com/piping-product/valve/