8900 Series Rev B Manway Emergency Relief Vents; Mates With API Flat Face Flange; 24" Size; 304 Stainless Steel Base; FEP Diaphragm; Model 8940 Non-Locking Hinged Pressure And Vacuum Relief Manway; 0.2 - 1 Oz/In2 Vacuum Spring Range; Epoxy Coated Carbon Steel Weight Material