Specifications Hign-concerned Chemical:None Type:Road Bike Freewheel is_customized:Yes Sensitivity:108 Sounds Flywheel Adjustable Gear Number:11/12 Material:Alloy Gear Teeth:11/12 Freewheel Speed:11/12 Origin:Mainland China Components:Freewheel ULT 11/12 Speed Road Cassette Ultraight Freewheel For Road Bike Material:high strength steel+aluminum alloy Compatibility: Road HG system(36.75mm hub body) Range:11-28/30/32/34/36T Weight: 11s 28T about107g(10g) 11s 30T about 110g(10g) 11s 32T about 113g(10g) 11s 34T about 132g(10g) 11s 36T about 140g(10g) 12s 28T about 122g(10g) 12s 30T about 126g(10g) 12s 32T about 127g(10g) 12s 34T about 142g(10g) 12s 36T about 147g(10g) The material of high tensile steel and aluminum alloy made by the technology of quench-temper hardening, makes it more durable and has extreme resistance to abrasion. *The unique design of the gear sprocket exclusively for mountain bike, provides you a better experience to control the shifter. Road HG Hub compatible Compatible with Road HG system(36.75mm hub body) Hollow design,steel+aluminum alloy combined,ultimate weight We adopted the hollow design to reduce the weight to some extent.