This piston ring seals the combustion chamber within the engine cylinder, preventing blow-by of combustion gases past the piston. It is a compression ring, the uppermost ring in the piston ring pack, and it transfers heat from the piston crown to the cylinder wall. A worn or broken ring causes a loss of compression, leading to reduced power, increased oil consumption, and visible blue exhaust smoke. The part is manufactured to the original geometry and material specification, which maintains the correct ring end gap and radial tension against the cylinder bore. On installation, ensure the ring is compressed evenly and that the end gap is within the specified range; do not reuse a ring that has been removed.