Comet Tribal Black Harley Davidson Brake Disc HD1508BK. COMET Brakes provide exceptional quality Floating and Solid Brake Discs which offer incredible performance for the price. 1x HD1508BK Black Tribal Design Brake Disc. Colour: Black (Tribal Design). Inside Bore: 56.4mm. You can send us a message by using the “Questions and answers” section towards the bottom of the page.