Allows you to sweep the center frequency (27–63 Hz) to align the bass restoration with your vehicle's sweet spot. 𝗨𝗻𝗹𝗲𝗮𝘀𝗵 𝘁𝗵𝗲 𝗟𝗼𝘄 𝗘𝗻𝗱: The patented bass restoration circuit detects upper-range harmonics and synthesizes a powerful low-frequency foundation.