The JBL GX328 is a 3-inch coaxial car speaker designed as an OEM replacement to fit 3-inch factory locations without vehicle modification. Power handling is 25W RMS and 75W peak, frequency response is 90 Hz – 21 kHz, impedance is listed as 2.3 ohms, and sensitivity is 89 dB at 2.83V/m.

The design uses Plus One polypropylene woofer cones for increased cone area and low-frequency output, an edge-driven soft-dome tweeter for improved high-frequency power handling, and low-impedance three-ohm DCR voice coils to extract more power from head units and amplifiers. Units are individually voiced and tested to OEM-level reliability standards for automotive use.