When evaluating a 6.5-inch subwoofer, you must prioritize Power Handling (RMS vs. Peak); ensure the RMS power aligns with your amplifier's output to prevent thermal failure. Pay close attention to the Voice Coil diameter and material (e.g., KSV or TIL) and the Magnet Weight (measured in Oz), as these directly impact heat dissipation and bass depth. Additionally, verify the Thiele/Small parameters (Qts, Fs, Vas) to ensure the driver is suitable for your specific enclosure type, whether sealed or ported.