BLACK DIAMOND DISCS. These award winning brake discs are made to the most exacting standards using computer aided design and computerised production whether you buy a Diamond X Drilled range for extra cooling, Diamond 6- & 12-Groove range for more instant response and greater friction or Diamond's award winning Combination range for extra cooling, extra friction and instant response you will always get Diamond's unique compound and extra heat treatment to provide you with awesome braking performance.