Amazon.com: 2PCS 40W 4Ohm 8Ohm Woofers Speakers 4 Inch HiFi Deep Bass Subwoofer Speaker 4 Layer Voice Coil Loudspeaker Car Subwoofer DIY (Color : 8Ohm) : Everything Else
B1240 subwoofer enclosure 12"/30cm 40 liters
Amazon.com: Bobtot Surround Sound Speakers Home Theater Systems - 700 Watts Peak Power 5.1/2.1Wired Stereo Speaker System 5.25" Subwoofer Strong Bass with Bluetooth HDMI ARC Optical Input : Electronics
GoldenEar ForceField 40 10" compact powered subwoofer with digital signal processing at Crutchfield
Focal K2 Power™ 40 KX 16" subwoofer with dual 2-ohm voice coils at Crutchfield
QED Reference Subwoofer 40 – fidelityhifi
GoldenEar ForceField 40 Subwoofer – Upscale Audio
1x 4.5" in 4Ohm 40W Super Bass Driver Audio Speaker Stereo Subwoofer Loudspeaker | eBay
Amazon.com: 2PCS 40W 4Ohm 8Ohm Woofers Speakers 4 Inch HiFi Deep Bass Subwoofer Speaker 4 Layer Voice Coil Loudspeaker Car Subwoofer DIY (Color : 8Ohm) : Everything Else
Subwoofer | Taramps Store
4Ω 4" Inch 40-100W Subwoofer Woofer High Power Long Stroke Speaker Loudspeaker | eBay