Monster Cable S16P-4-500 Monster Standard Plenum Four Conductor UL CL3P Rated Speaker Cable 16 Gauge Plenum (500 ft. spool) Tightly twisted inner conductors for increased rejection of interference 16-gauge construction with ultra fine, high-purity copper stranding 4-conductor CL3P rated for in-wall installations Color-coded red/black and green/white inside pairs for easy identification Economical and convenient to run 2 channels in one cable