Shimano CS-R9200 Cassette Spacer B Description: The Shimano CS-R9200 Cassette Spacer B is a factory replacement part that can be used to replace a damaged or missing spacer from the Shimano CS-R9200 12-speed road bike cassette. Installing this part with the rest of the cassette ensures proper spacing between the cogs for optimal shifting performance and drivetrain durability. Features: Spacer B is specifically designed to ensure the proper spacing between the 8th and the 9th cogs (1st cog is the largest one, and the 12th cog is the smallest) Spacer is sold individually See compatibility tab for full list of compatible cassettes