Disc is the smallest 360o ceiling-mount PIR detector available today. Boasting a miniature size of 8.6cm (3-3/8 inches) and sleek elegant design Disc blends inconspicuously into any d?ecor. Into this miniature unnoticeable housing Visonic packs a powerful combination of features for maximal performance reliability and false alarm immunity. Standard features include: a high-quality low-noise dual-element detector; 360o detection pattern; floor coverage of up to 10.8m (36 ft) adjustable pulse counter and more.