Infinity Reference 6422cf 4-Inch x 6-Inch Two-Way Loudspeaker (Silver/Black) Plus One woofer cone technology gives improved bass response over convential speaker designs The Edge-driven textile-dome tweeter gives outstanding high frequency performance The speakers are designed to be driven with a 2 ohm amplifier or head unit; this will give you improved bass response than a conventional 4 ohm speaker system ; the speakers can also operate at 4 ohms Polypropylene Woofer Cone for improved bass output The speakers can be driven by a factory deck as wells as an aftermarket head unit