4 G-----Shimano BR-R451 Road Brake CalipersCompatible with STI and brake levers that are Super SLR enabled (e.g. Dura Ace Di2 7970, Dura Ace 7900, Ultegra Di2 6770, Ultegra 6700, 105 5700, Tiagra 4600)Light action and accurate brake powerAdjustable toe-in brake shoesUse of these calipers with standard SLR enabled STI and brake levers results in a "mushy" brake responseItem SpecificationsBrake Lever ActuationShort Pull Super SLRBrake Mount TypeMid Reach Caliper (47mm - 57mm)Brake PositionRearDefined ColorSilverPad TypeCartridge-- 4 G---1309964 (274 - 277) 3/27 #60120:10 90820(5:9/11b/o -----1: rtn 12/9--1:rtn on 1/1---- RTN ON 5/17----5:6/24:ari---p.o.#52421 40323(3:4/5/23:ARI