Massive Audio MX Series 4-Inch 40-Watt-RMS 2-Way Coaxial Speakers in the Mobile Audio department at Lowes.com
Ghxamp 1pc 4 Inch 40w Subwoofer Speaker Woofer High Power Long Stroke Bass Home Theater For 2.1 Subwoofer Unit Loudspeakers Diy - Speakers - AliExpress
Current Audio SB65 40 Watt Amplified Soundbar & Wireless Subwoofer Electronics - Zavvi US
1pcs 4 Inch 6 Ohm 40w Bass Speaker Woofer Subwoofer Long Stroke Hifi Audio Loudspeaker - Speakers - AliExpress
Amazon.com: JINGERL 40W Subwoofer Speakers 4 Inch 4Ohm 8Ohm HiFi Woofer Speakers Deep Bass Bookshelf Loudspeaker Glass Fiber Basin Home Theater DIY (Size : 4Ohm Square 1pc) : Electronics
Amazon.com: 5 CORE 4 inch Speaker Driver 40W 4Ohm Replacement Full Range Audio Stereo Dual Cone Concept for Extra Crisp Sound Made in India (Pair) : Electronics
Polk Audio DB1242SVC 12” 1110 Watt Single 4-Ohm Car Audio Subwoofer Sub+Speaker | Audio Savings