Thorburn Retrofit Seals are specifically designed to solve union leak problems caused by sealing surfaces thatare pitted, scratched or rusted by changing the metal-to-metal seal to an O-Ring seal (like a hydraulic fitting).Fits MSSPC-83, 3000 lbs (200 bar), 300lbs (20 bar), 150 lbs10 bar unions.Retainer ring plated steel or 316SSO-Ring material BUNA N, Fluorocarbon