Replacement cog for 11-speed SRAM and SunRace cassettes.
Remove the 17 and 19t cogs and replace them with the 18t for GC49 conversions.
These are specifically designed for use with SRAM and SunRace cassettes. The clocking, or rotational orientation, between SRAM and Shimano cassettes are much different so optimal shifting cannot be achieved unless the design is optimized for each separately.
SRAM 11 speed cassettes
SunRace 11-speed cassettes