Ventilation & Adjustment---Our window restrictors are adjustable and can protect children while meeting the function of ventilation. There are two different opening sizes to choose from, 9.2cm and 13.5cm. Hold the sliding button on the rod to slide or pull the window, allowing you to adjust the opening size of windows. Why is it needed - Prevent children from getting their hands pinched by opening and closing windows without adult supervision; prevent children from climbing on windows; prevent toddlers from accidentally falling out of windows. It is effective not only for children, but also for pets. Universal & Durable---Made of PA+ABS material, the window restrictors are strong and durable with two parts. Our window locks can be used for windows that open inward and outward. Installation Tips --- Screws and 3M VHB transparent adhesive are combined to achieve the best installation effect. 3M VHB transparent adhesive has super adhesion (the effect is better after 24 hours) and can be easily removed without leaving any traces. Easy to use: The window restrictors can be easily unlocked without the need for a key. Press the two buttons on the lock body and push the window to unlock it, so that the window can be fully opened as usual. Easy for adults to use but difficult for children to open, providing effective protection for children.{PL}