The shimano dura ace 9100 11 speed cassette 11 25t is a super lightweight 11 speed hg ev cassette with a rigid carbon and alloy carrier for excellent shifting shimano dura ace 9100 11 speed cassette features super lightweight 11 speed hg ev cassette with a rigid carbon and alloy carrier for excellent shifting even under the most demanding gear changes hyperglide ev sprockets have a computer designed tooth configuration with contoured shift gate