The LS, Low Shrinkage compounds are designed to give part shrinkage (out of the mold) and post-curing operation comparable to a nitrile or similar elastomer. In most cases, tooling changes are not required when switching over to an LS compound. NPC indicates no post cure required to achieve high tensile and modulus values with good compression set and aging characteristics. FKHT is a high temperature resistant, low compression set compound. FKX is a high viscosity, high green strength, black fluorocarbon compound formulated for HAV and / or salt bath curing of O-ring cord and extruded profiles.