RCA Cables:
These are the cables used to transfer pre-amp (line level) signals. Usually, you use this type of cable for unamplified signals such as the connection between your head unit and amp or crossovers/eqs. Look for appropriate thickness and shielding. The end connectors should be sturdy to prevent breakage from stress. Some claim that very expensive cable makes a difference in sound quality. I do not think so, do not spend more than $1/foot. You may need to spend more to get cables that are more immune to noise if you have that problem in your car