JL Audio 10TW3-D4 Shallow-mount 10" subwoofer with dual 4-ohm voice coils at Crutchfield
MTX FPR10-04 SHALLOW MOUNT 10" SUBWOOFER SINGLE 4-OHM 600 WATTS FREE SHIPPING | eBay
Amazon.com: JBL Club WS1000 10" Shallow Mount subwoofer w/SSI (Selectable Smart Impedance) Switch from 2 to 4 ohm Bundled with Alphasonik Earbuds : Electronics