YOKOMO FRONT & REAR BRAKE DISK, CALIPER SET FOR YD-2 SERIES (Y2-415CPA) The brake discs themselves will include an integral hexagonal hub to be able to mount the wheels. There will be 3 types of hub thickness, 5.5 mm, 6.5 mm and 8.0 mm which will all be included so track width and scrub radius can be adjusted freely. The brake calipers, which can be mounted to new front and rear knuckles, are gunmetal color to better represent the realistic look and finish of a real car. Brake discs & calipers looking through the gap between the wheels will give your chassis a true realistic scale look!