689-631, RS PRO, RS PRO Nitrile Rubber O-Ring O-Ring, 3/8in Bore, 1/2in Outer Diameter, Brand RS Pro, Type O-Ring, Material Nitrile Rubber, Inside Diameter 3/8in RS PRO Nitrile Rubber O-Ring O-Ring, 3/8in Bore, 1/2in Outer Diameter