The Model UG-BB-3X20 Bandit Bar (alarmed window bar)kit includes 3, 20" (50cm) bars, you assemble to length needed. Protects a window up to 60"(150cm)wide and 14"(35cm) high. Both sides of a sliding window are protected, whether the window is open or closed. Works with any system. Made of strong extruded Aluminium, will not sag or flex with heat. Can be installed horizontally or vertically. Provides a visual deterrent from outside the home and will trigger an alarm if dislodged or cut. works great for skylights,roof hatches and air ducts too!