Appearance: Professional surface treatment, firm, simple and beautiful; Made of highquality materials, easy to open, suitable for most plastic steel alloy windows. Safety: To prevent burglary, the window can be locked when it is half open. To prevent children from falling due to heavy weight, avoid accidentally opening the window for children Function: The secondary lock adds safety when ventilating or fixing your sliding door or window. Easy to install: No additional tools are required, no drilling is required. Open the window to the appropriate position or close the window as needed. Adjust the spacing of the window lock, put it on the window frame, insert the key, turn the key clockwise or counterclockwise, and adjust the width to fix the lock. Turn the key until the key slot cannot move, which can make the window lock work effectively. Ventilation: It can fix the window in place, will not be pulled open or opened, keep ventilation, effectively prevent your children from opening the window by themselves, antitheft, and keep fresh air indoors.