E*thirteen Extended Range Cog. Features: Extended range aluminum 42t cog to fit Sram 10-speed cassettes 42t is compatible with 36t max cassettes Remove the existing 17t and add the Extended Range cog without any additional spacers to create an 11-42 10-speed cassette option Cogs come with a longer replacement B-limit screw, to avoid running the derailleur with the stock screw maxed out Intended for use with 1x drivetrains. Chainwrap capacity will be an issue for those wanting to use double cranksets Specifications: Teeth: 42t Color: Blue Version: Sram Weight: 70g