4PCS Right Window Restrictor: The window limit lock is suitable for casement windows, limits the opening angle of casement windows, prevents children or pets from falling from the window, and prevents the sash from falling. It includes safety pins and safety hook in two parts. The window opening range is limited to 100mm. Automatically re-engage the Restricted Position: It can be released to facilitate the full opening of the window When the window is closed, the restricted position is automatically re-engaged for our convenience. 304 Durable Stainless Steel: These security window plugs are made of 304 stainless steel, which has excellent corrosion resistance, high toughness and rust resistance, which can extend its service life. Easy to Use: Just install it on the window with a screwdriver. (Including screws). Protect Your Safety: This window stopper is ideal for home, kindergarten, school security and other applications.