High quality material: The sliding window door lock is made of aluminum alloy. Window locks are thickened, wear-resistant, durable and sturdy. Before ordering a child and pet safety window lock, make sure your window rails exceed 0.6 inches/1.5 cm in height and 0.63 inches/1.6 cm in width Packaging information: You will receive 4 sets of window locks for sliding doors and windows, which include 4 door and window lock blocks, 4 hex keys, 4 protection washers and 1 vertical key. These sliding door locks with key can meet your needs Protective Washers: Each sliding door lock window frame stopper is equipped with a plastic protective washer to prevent scratches of the window when you turn the screws in stainless steel on the window guide rail. The protective washers can provide friction force between the window lock and the guide rail to ensure that the window does not slide Easy installation: The window lock is suitable for sliding windows and sliding doors. Place the protective pad in place to avoid scratching the window, place the window lock in place and turn the key to secure the window lock. Remember to take care of the keys Safety: Window locks prevent children or pets from accidentally opening windows and avoid accidents. Window locks also protect against thieves. Multiple window locks can be attached together for added security if needed