The Factory plastic OEM breathers can be problematic as the material easily distorts, especially after seeing excessive heat. Then the internal umbrella valve struggles to seal, causing oil carry over. Another issue found with the OEM breathers is cracked and or broken exit nipples which can be caused by heat distortion and or improper fit and poor installation. Feuling cylinder head breathers are machined from billet 6061 aluminum with square surfaces, promoting excellent umbrella valve sealing, longer main breather exit nipples with dual O-rings to promote better breather system sealing. Properly sized breather inlets and location for optimum engine breathing. Unique design maximizes breather volume and allows for easy serviceability. Breather bodies have multiple drain ports located on the inside lower, ports are chamfered on ID to allow easy drainage yet squared off on exits to deter filling from splash oil. Anodized Feuling red. Kits include: billet breather housings, billet covers, breather filter elements, umbrella valves and quality hardware.