Moroso introduces GM COPO replacement valve cover breathers, Part No. 68857, Two Pack. They replace damaged COPO breathers, a good addition to back up engines or for new builds where the goal is to breath the engine the same way as the COPO cars. Breather screws on to factory COPO breather covers or Moroso Part No. 68493 valve covers that accept COPO breathers. Breather's fitting accepts a 5/8" hose.