Review on DROK 4 Inches 4 Ohm Audio Speakers for Cars - 40W Anti-Magnetic Car Stereo Speakers with 87dB High Sensitivity, Thumping Bass, and Loudspeaker Subwoofer - Ideal for 2.0/2.1 Home Stereo, DIY Boombox, and Satellites by Samuel Nguyen

Installed two of these 4 inch woofers in a special ammo box Bluetooth ammo bank, 2 inch ID port. The sound they make is amazing. These are woofers at around 87dB but with a good amp they produce great and smooth bass and mids for such a small size! Are those subwoofers? no Great sounding 4" woofers. Yes! I had to make a special crossover for the tweeters. I used 7.5 ohm resistors (25W) and 10uF capacitors. The amp load impedance was set at 3.8 ohms Tweeter Great balance and crossover ammunition tuned to 48Hz It's doubtful this woofer will run that low but for me it's a darn good balance I'm 50 years old with about 35 years of experience in FWIW electronics and speaker assembly .