Big, bad bass � You can't get any lower than this: These extraordinarily powerful subwoofers are perfect for reproducing the strong low frequency output of the Bass Engine® head units and the V12 amplifiers. Exceptionally strong and durable � thanks to the Kevlar reinforced pulp cone � they also feature a high excursion Santoprene® edge, delivering over 2" peak-to-peak excursion.Cone and Edge: By reinforcing the cone pulp with Kevlar, strength and tear resistance are increased while retaining the beneficial qualities of a pulp cone design. The use of Santoprene®, a precision-molded high quality synthetic rubber, allows thicker sheets to be molded into stable edges with increased strength and higher excursion.Nomex® Spiders: Dual spiders provide extra stability to Alpine's high excursion design, by keeping the coil centred in the gap even when driven to the limit. Additionally, custom oversized progressive spiders were tooled to evenly distribute stress through the long stroke. Constructed of Nomex, the toughest spider material available, tear resistance, strength and durability are outstanding. Dual Custom Progressive.Custom Cast Aluminium Frame: Aluminium is well known for its high thermal conductivity in amplifier heat sinks, and is no different in Alpine's exclusive thermal control system. Visually stunning, the Type-R frame's unique design also provides ample strength for its massive double stack magnet motor assembly. No spider spacers here, as the deep spider landing was designed for high excursion from the start.