These are the seals many of you have heard about, which will once and for all cure the notorious intake leaks of Linkert manifolds. They are machined from PEEK (polyetheretherketone), a thermoplastic with a melting point of 650°F (343°C). Compared to brass seals this material has superior creep resistance and seal properties and can sustain large stresses over a long service life without significant extrusion.