This is a passive speaker that needs to be used with a subwoofer amplifier, and it does not have a crossover.
The subwoofer unit has a special low frequency enhancement design that is not as simple as a high power long stroke. With a good cabinet and guide, bass dive, flexibility, and strength are just right. Whether it is a 2.1 system subwoofer or a 5.1 system subwoofer, it has a very good performance. Of course, you can also use it to supplement the low-frequency part of the full-range speaker.