LFDriver 40CM XSP15A 4Ohm - Part of XSP-15A 15" powered speaker
Epique E150HE-44 5-1/2" DVC MMAG Extended Range Subwoofer 4 Ohm per Coil
Amazon.com: Ground Zero Iridium 16,5 cm / 6.5" Subwoofer - 4 Ohm - 100 WRMS : Electronics
LAV FSN041.00: Full-range speaker, 40 W, neodymium, 4 inch (10 cm), steel at reichelt elektronik
Amazon.com: H YANKA 12 Inch Subwoofer - 12 Inch Paper Cone Subwoofer Car Audio, Black Steel Basket, Dual Voice Coil 2 Ohm Impedance 12 subwoofer, 1800W MAX Power 12 inch Competition Subwoofer : Electronics