The 1000S is Infinity's latest Reference subwoofer offer incredible installation flexibility. Their low-profile design allows them to fit perfectly into even the most shallow of enclosures – great for today's compact cars. Polypropylene woofer cones deliver exceptional bass response at frequencies as low as 27Hz. But what makes these subs really stand out is their Harmanproprietary SSI™ (Selectable Smart Impedance), which allows the subwoofer to present the amplifier with either a 2 or 4 ohm load at the flip of a switch.