Abstract: A movable-window safety device for arresting upward movement of a power-driven window glass in a motor vehicle body in the event of obstruction in the window opening comprises a resilient channel for receiving the window glass and which is mounted in a rigid window frame. The base of the resilient channel comprises an electrical detecting member housed in a hollow chamber. The side walls of the resilient channel extend proud of the sides of the rigid window frame and carry curved-over outer lips and inner lips. An obstruction in the window opening is carried upwardly by the window glass and applies a force to one or other of the side walls of the resilient channel, according to whether the obstruction extends inwardly or outwardly of the window opening. The resultant force is applied to the detecting member.