Shimano zee m640 disc brake rotor bundlenew zee hydraulic disc brake systems are gravity rated with a servo wave brake lever and new 4 piston ceramic disc brake caliper system stiffness is tuned using shimanos high power hose and shorter lever blade while ergonomics are perfected with a new pivot location and dimpled surface ice tech brake pad and rotor options reduce heat in the system and maintain performance on the longest descents shimano introduces zee a new line of gravity components