These Head Gaskets Do Not Require O-rings in the block or head, and they require no additional sealant. Patented Integral Combustion Seals found only on ICS Titan head gaskets take the place of O-rings in the block or head, with an added benefit. The illustration shows how the solid gasket body is cut and separated for insertion of a stainless O-ring wire. Primary combustion sealing is achieved by load concentration from the inserted wire as in the case of an O-ringed block. In addition, the upper and lower flanges of the ICS combustion seal remain open toward the cylinder allowing the pressure of combustion to force them against the block and head.