First, thanks for the question. There are a few different caliper styles: floating calipers, fixed calipers, open and closed calipers, monoblock (from billet) calipers and calipers with one or two bridges. But radial-mount systems are, as far as we know, the best. The advantage, compared to any perpendicular mounting system, is better rigidity. Pad pressure on the disc is more evenly distributed, which minimizes the pad taper that tends to occur between the entry and exit pistons. Properly engineered piston sizes further diminish pad taper. The leading piston is always smaller than the trailing piston.