Keeps doors and windows open. The Nessa hinge lock is an all-round talent. Simply hooked onto the hinge of the door or window, Nessa prevents doors and windows from suddenly slamming shut due to a gust of wind, for example. This prevents small children and babies from becoming trapped in the door or window and possibly injuring themselves. Tip: If you purchase the optional counterpart, you can attach the Nessa hinge lock at any position on the door and window frame.