GD Drilled & Slotted Discs - EBC-s unique wide aperture slots actually pull cool air under the pad surface and help pad and disc cooling. The (Blind Drilled) dimples help break down surface gases but do not promote cracking, which has been shown to occur with (Through Drilled) discs. A unique feature of the Groove Disc is that the slots extend completely to the outer edge of the disc which allows any dirt, dust gases, grit or debris from heavy braking to exit the pad braking area. This ensures flat and parallel wear of the pads throughout their wear life and use.