Shimano SM-RT900 Dura Ace Center Lock Rotors: Ice Tech Freeza rotors provide consistent braking performance through energy control, using revolutionary stainless steel and an alloy 3-layer sandwich construction that manages heat while riding. The clad steel/alloy/steel rotor construction allows heat generated from braking, to radiate quickly through the aluminium core dropping the surface temperature around 50°. When used with Ice Tech pads the surface temperatures can drop from around 400° to 300°, this provides great improvements in all round performance.