TRP L4 180R Post/Is 74Mm Is Disc Adapter Post Mount

The TRP L4 180R Post to IS Disc Brake Adapter is a CNC-machined aluminum adapter engineered to bridge different mounting standards on a bicycle's braking setup. It allows you to mount a standard modern 74mm Post Mount caliper onto a traditional 51mm International Standard (IS) rear frame mount when running a 180mm rear rotor.