Material: The mountain flywheel is made of high-quality steel, which is durable and not easily damaged. It is durable and has a long service life Excellent speed change: Road Bicycle Cassette has excellent speed change performance, with excellent gear design, which can prevent the chain from falling Application: It is compatible with S-r-a-m and S-h-i-m-a-n-o bicycle flywheel transmission. This is your ideal mountain bike variable speed flywheel replacement accessory Color: The color is colored, and each cassette gear has a different color. Bicycle freewheel is very stylish and cool and can decorate your bike more beautifully Speed ratio: 12S-50T 11-13-15-17-19-21-24-28-32-36-42-50T. 12S-42T 11-13-15-17-19-21-23-25-28-32-36-42T. It can meet your various gear shifting needs during riding Description The mountain bike flywheel is made of steel, durable and not easily damaged. long lasting. Its color is colorful, and each of its cassette gears has a different color. Mountain bike 12-speed 11-42T/50T freewheel is very stylish and cool, which can decorate your bike more beautifully. Features Product name: RETROSPEC-12 speed aluminum frame cassette mountain flywheel 11-50T colorful Number of teeth: 12S-50T 11-13-15-17-19-21-24-28-32-36-42-50T 12S-42T 11-13-15-17-19-21-23-25-28-32-36-42T Caliber: 22.2mm (standard), cassette type Material: chrome molybdenum steel chainring/aluminum alloy/hollow design Process: Colorful electroplating/one-piece forging Applicable: 12/24/36 speed mountain speed change of SHIMANO, SARM, etc., professional climbing Weight: about 585g, packed in PE bag Color: seven colors Package Including 1 * Road bicycle cassette