The HS1 is the new Avid rotor designed with cross drilled heat shedding technology. This new rotor also provides measurably better performance in wet weather conditions. Light weight for going up, strong and performing for doing down.
Note: For 2012 Avid has realigned their rotor sizes to be 140, 160, 180 and 200. The new 180 and 200 rotors will not worth with old 185 and 203 adapters. New adapters will need to be purchased.