NEW Unopenable Window This is a window auxiliary lock from Mitsuki Corporation. Set of 3. 【Product Description】 Installed on windows to guard against external intrusion. Locks the window to prevent it from opening, for home security. Applicable dimensions are approximately 28-42mm. Suitable for both upper and lower frames. Easy installation, no tools required. Can be used for crime prevention and to prevent young children from opening windows without permission.