What exactly are 2 piece rotors? Ive heard the term before but never looked into seeing what they are, or how they are better compared to regular rotors. Do they offer better braking, and are they really 2 pieces?

 

They have separate rotor hats and discs. The hats are generally aluminum, saving weight while the discs are steel. Also since the disc is replaceable on its own you can save some money during replacements, or have different types of discs for different conditions. The benefit to braking is minimal and basically all due to the reduced weight of the hat.