Adapter for mounting flat mount disc brakes to frame of post mount base. ・Requires a + 0.8 inch (20 mm) sized rotor before using the adapter. (If using 5.5 inches (140 mm), it will be replaced with a 7.1 inch (160 mm) and 6.3 inch (180 mm) rotor). *For installation, please refer to the 5th picture of the 5.5 oz (17 g). Material: 6061-T6 aluminum. Compatible Rotor Size: 5.5 inches (140 mm), 60 mm, 160 mm, 160 mm, 160 mm, 180 mm, 180 mm (180 mm (180 mm (180 mm (180 mm before using the adapter).