The main functions of the screen window lock can be summarized as follows: 
Safety protection 
Prevent children or pets from accidentally pushing open the screen window and falling, especially essential for high-rise residences. Some locks are designed with child-proof features and can only be opened by adults. 
Anti-theft and anti-intrusion 
Increase the difficulty of damaging the screen window, delay the time for thieves to dismantle or cut the screen window from the outside, and it is usually used in combination with diamond mesh screen windows to enhance the overall anti-theft level. 
Stable seal 
When there is a typhoon or strong wind, lock the screen window to prevent it from being blown and making noise or deforming. At the same time, it enhances the tightness between the screen window and the window frame and reduces the air leakage through the gaps. 

Function Expansion 
Limited ventilation: Some locks can adjust the opening angle to achieve micro-ventilation and prevent outsiders from entering. 
Mosquito prevention upgrade: Secure the screen window to prevent any gaps from forming between it and the window frame, thus stopping mosquitoes from getting in. 
Special scene requirements 
For outward-opening windows, the screen needs to be pushed up from the bottom to be removed. The lock can prevent others from easily removing the screen from the outside (commonly seen in shops or low-rise buildings). 
Common types include push-button, rotary, latch, magnetic lock, etc. When choosing, it is necessary to match the material of the screen window (such as plastic, aluminum alloy) and the installation position (frame or bottom).