Low-profile design Because today’s compact cars offer less space, the JBL Club Subwoofers are designed to fit into small enclosures. They’re slim, sleek, stylish, and don’t sacrifice on sound. Harman-proprietary SSI™ (Selectable Smart Impedance) Unlike most dual-voice coil woofers, which provide either 1 or 4 ohms or 2 or 8 ohms, the JBL Club Subwoofers allow the listener to 2-ohm and 4-ohm at the flip of a switch, providing the two most often used impedances from a single woofer. This allows the system designer unparalleled flexibility in extracting every last watt from your amplifier without compromising stability and thermal safety margins. Frequency response as low as to 27Hz Your audio is filled with delicious sounds. Unfortunately, you’re not always hearing them all. With lows that dig down into the depths of 27Hz, you’ll hear the low-end frequencies you’ve been missing. OEM-level reliability testing JBL tests every speaker design to the same rigid specifications as the automakers, subjecting them to extreme conditions that would break lesser speakers. We freeze them, bake them, shake them, blast them with ultraviolet light and drive them at full power for days to make sure your audio investment lasts for years.