Amazon.com: Alpine SWA-12S4 BassLine Series 12" 4-ohm Subwoofer : Electronics
Amazon.com: PyleUsa 10-Inch Low-Profile Amplified Subwoofer System - 900 Watt Compact Enclosed Active Underseat Car Audio Subwoofer with Built in Amp, Powered Car Subwoofer w/Low & High Level Inputs - SBA10A :