Spy 4 is the world's smallest detector offering inconspicuous curtain protection for corridors, passageways, doors and windows as well as support for access control, CCTV and various other control applications. It can be flush-mounted in a wall or ceiling or installed from behind the wall or the ceiling, providing a solid-curtain coverage of up to 2m width x 4m height (6 x 12ft).Despite its miniature size, the Spy 4 detector achieves full-size performance by implementing state-of-the-art detection technologies. Backed by 30 years of Visonic expertise, Spy 4 offers industry-leading sensitivity and reliability levels while virtually eliminating false alarms. Spy 4 is ideal for perimeter protection, securing corridors, doors, windows and skylights as well as controlling CCTV, access control and other systems. It is designed for trouble-free ceiling or wall mounting. Mounted so only the miniature lens is visible, the Spy 4 detector is virtually unnoticeable after installation.