Adjustable Window Gap Size --- With thewindow restrictor,two different window opening size can be choose, 3.62""(9.2cm) and 5.31""(13.5cm). The adjustable window gap size can meet the daily ventilation requirements and more customers' needs. Why it is Necessary---The window lock is strong enough as it is made of polyamides material.Feel free it can prevent kids from playing the windows and pinching their fingers;prevent kids falling out of the windows and etc. Not only for babies but also for pets. Easily Lock Unlock---Press the double button to unlock the lock , and the window can be open or close freely. No key or other missing parts with the installed lock. Adjust the window gap by press and hold the slider button on the pole and push or pull the window.Easy for adults to use but hard for babies. Easy to Install Tips--- Window restrictor provide tapes and screws for customers to install.With the tapes it can bear at less 58 LBS (Effect will be better after 24 hours).Pls select the suitable install method base on the actual requirements. Wide Application Range-- -Used for inside opening windows and outside opening windows.Fits most windows in the market.