Anti-theft and SecurityThe lock angle is smooth, not hurting the hand. Lock buckle reinforcement design, not easy to fall off, durable. Anti-collision pad at the bottom of the handle to prevent scratching the window frame. It is suitable for all UPVC doors and windows. Quality guaranteedStrong window lock made of zinc alloy, durability and quality guaranteed, white powder coated, a good match with windows and doors . Easy to use180 degree rotation design, it can be docked at any angle. Simply twist the interference arm to lock or open the chassis. Easy to InstallClean the surface of the mounting location - Screw it in with a screwdriver - Hide with the screw cap supplied - finish to start security guarantee. NoteOnly use for casement windows and doors, do not adopt to sliding windows. Easy to use Comes with mounting screws and button gaskets, the chassis stops are easy to install with the supplied mounting screws. How many blockers should I install on my door or window? Single doors will normally have two blockers fitted one mounted in top and one rise at the bottom of the door. Small windows only require a sash blocker to install. Patio doors and French doors will have 4 mounted on each door, two on top and two on the bottom. Door and window lock Durable design Made from sturdy cast zinc with durable powder coated finish. Durable and stable What are the advantages of the Sash Jammer? Door jammers are a cheap way to improve the security of your uPVC door or window Easy to install S' fits most types of doors and windows Fits doors and windows that open inward and outward Reversible, suitable for left and right-handed doors Can prevent the door or window from opening if attempted break-in