Shimano SM-MA F180P/P2 Disc Brake Adapter

Postmount Adapter for using a larger brake disc rotor. For connecting a Post Mount fork or frame with a Post Mount brake caliper. The adapter can be used as follows:

Specifications
140 mm fork mount - for using a 160 mm brake disc
160 mm fork mount - for using a 180 mm brake disc
140 mm frame mount - for using a 160 mm brake disc
160 mm frame mount - for using a 180 mm brake disc