Aiflon Serrated Metallic Gasket is the preferred gasket when improved performance at low seating stresses is required. It features excellent anti-blow-out properties linked with the reliably of a solid metal-to-metal seal combined with a soft sealing face to provide a tighter joint.  It is particularly suitable for applications where high temperature, pressures and fluctuating conditions are encountered. Non-metal cover layers ensure that flanges are not damaged, even at extreme loads. This gasket is an ideal replacement for problem applications associated with jacketed gaskets, for heat exchangers, vessels and reactors and various flange connections. (Pressure: (6.4~25Mpa)

The thickness of graphite or PTFE face is normally 0.5mm.
Depending on centering ring with cheaper material (Normal: CS) and thinner thickness (Normal: 1.5mm) for Style 6400 SJ,  maybe it is more economical than 6400JR.