Hertz DCX 690.3 Dieci series car audio coaxials use an oversized magnetic group, TPU (Thermoplastic polyurethane) surround, a 60 mm diameter midrange, and a PEI dome tweeter. The result is linearity, wide dispersion, and extra-ordinary efficiency not found in traditional coax components. An involving, emotional sound, even at high SPL levels. An authentic 3-way coax capable of reproducing a wide frequency spectrum.