It's easy to recognize an LRD ported cylinder. Like many companies, LRD marks the barrel with a serial number that provides vital stats for that specific build. This way, with a simple phone call, LRD knows exactly what you have and what has been done to the bike. The stock head was replaced with the Pro Design Cool Head since we find that the Cool Head helps reduce water temp. The head shell holds and moves more coolant than stock and uses O-rings to seal rather than a head gasket. The elimination of the head gasket removes a heat barrier between the cylinders and the head, allowing the relationship between the head and cylinder to be more thermally efficient. The Cool Head's interchangeable combustion chambers allow compression to be adjusted to match altitudes and fuel octane.