TKO12S4 - 12" 300 Watts RMS Single 4 Ohm Subwoofer
Dual Voice Coil Subwoofer Wiring Guides - Skar Audio Knowledge Base & Help Desk
Amazon.com: Pair of Gravity 15 Inches Car Audio Subwoofer 3200 Watts Peak Power (1600x2) RMS Power 80 Watts Each with Dual Voice Configuration 4 Ohm Power (2 Woofers) : Electronics