Premium Wire Harnesses, are the upgraded Factory or Amplified Systems. These are needed if your system is NOT a base model, or if you have Specialized electronics like; Onstar, SYNC, CANBUS, LAN, R.A.P, VSS (or) Factory Amplified; Bose, Monsoon, Audiophile, Infinity, JBL, Symphony-Concert, Harmon-Kardon, Pioneer (these all require specialized harnesses).