Product Description Our shielded 500 foot gray 18 AWG (American Wire Gauge) 4 conductor stranded security/alarm wire comes in rugged spools. This wire is CM / in-wall rated; it is not intended for plenum or riser situations. The shielding is an aluminum mylar designed to prevent electrical interference in noisier environments from disrupting signals from devices. This security wire is designed for use in security/alarm systems. It is typically used for connecting motion sensors, keypads, magnetic contacts, glass breaks (acoustic detectors), smoke detectors, communicators, sounders/strobes, entry management and control panels in such systems. When wiring a system please be sure to consult the manufacturers' recommendations for wire conductors, gauge and expected resistance.