Sound modification: 6.5-inch coaxial mid-bass speakers for cars, with two-way or three-way frequency division.

Three-way frequency division car speaker system. 6.5-inch mid-high frequency car door speaker set. 

It has both treble and bass, and one is equivalent to two:
The coaxial speaker integrating treble and bass combines advanced acoustic technology. This enables almost perfect cooperation during the transmission and conversion of audio signals. When playing music, the clear and bright treble and the deep and mellow bass are naturally and smoothly integrated without any sense of abruptness, bringing you a shocking auditory experience with seamless sound transition.