Ventilation & Adjustment---Our window restrictors are adjustable and can protect children while still allowing ventilation. Two different opening sizes are available: 3.62" (9.2cm) and 5.31" (13.5cm). Press and hold the slider button on the pole to push or pull the window, adjusting the opening size. Why you need them? - Prevents babies from getting their hands stuck when opening and closing windows without adult supervision; prevents babies from climbing on windows; prevents toddlers from accidentally falling out of windows. They are effective not only for babies but also for pets. Universal and Durable---Made of PA + ABS material, these window restrictors are strong and durable, with two parts. Our window locks can be used for windows that open inwards and outwards. Installation Tips --- Screws and 3M VHB clear adhesive are combined for optimal installation. The 3M VHB clear adhesive has excellent adhesion (best after 24 hours) and can be easily removed without leaving any residue.