Shimano CS-R9200 Cassette Spacer A Description: The Shimano CS-R9200 Cassette Spacer A is a factory replacement part that can be used to replace a damaged or missing component within select Shimano 12 speed road and gravel bike cassettes. Installing this part with the rest of the cassette ensures proper spacing between the cogs for optimal shifting performance and drivetrain durability. Features: Spacer A is specifically designed to ensure the proper spacing between the 9th and 10th 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