FIRST MEASURE YOUR DOOR THICKNESS BEFORE PURCHASING THIS 2-PACK. Fits most hinged doors up to 1-3/8 inches thick (or up to 1-13/16 inches thick when GlideLok's spacer bar is removed). Fits exterior and interior doors, French doors, and doors with levers, oversized/unique handles, and knobs. Does NOT fit any sliding door on a track, such as pocket doors, bifold doors, or sliding glass doors. Also does NOT fit storm doors, patio screen doors, metal door frames, or double doors that swing in both directions. YOU MUST DRILL ONE SCREW (INCLUDED) INTO DOORFRAME. Most exterior doors require the screw to be drilled on the outside/exterior portion of the door frame. (But you can still operate the GlideLok from both sides.) Make sure you can reach the top of your door in order to operate the GlideLok. PARENTS CAN EASILY LOCK AND UNLOCK FROM BOTH SIDES OF THE DOOR. Unlike other door handle childproof locks, you will not get stuck on the wrong side while your toddler is left alone, separated from you. Also, if you don’t need the door locked for a while, just leave the GlideLok unlocked, and you can open and close the door as usual until you are ready to lock the GlideLok again. SITS ON TOP OF THE DOOR SO CHILDREN CANNOT ACCESS IT. The GlideLok rests on top of the door and overhangs both sides, similar to a saddle. This sets it apart from most childproof door lever locks or door knob child proof locks, because kids cannot try to destroy it or take it apart. Also, the GlideLok’s subtle appearance fits nicely with any home décor. LONG-LASTING METAL WILL NOT FLEX OR BREAK LIKE FLIMSY PLASTIC LOCKS. GlideLok is the original top of door child safety lock made of durable, painted metal, not cheap plastic. So it will keep your children and toddlers safe for many years. Use to secure doors throughout your home, including the basement, laundry room, pantry, bedroom, front/back door, and more. The GlideLok child safety lock for doors is a child safety door top lock, so it is out of reach for toddlers and small children. This works better than making your door latch lock child proof or installing a childproof door knob cover, since kids cannot even reach the GlideLok to try to dismantle it. A metal screw (covered by a metal sleeve) will be screwed into your doorframe, and the GlideLok slides around the sleeve to lock and unlock the door. This child door lock will fit thicker, exterior doors as well as interior doors. The GlideLok toddler door lock is made of weather-resistant, durable painted metal. This child lock for doors works on a variety of doors, including French doors, basement doors, pantry doors, bedroom doors, and laundry room doors. The Glide Lock Child Safety Top Lock fits doors up to 1-3/8” thick (or up to 1-13/16” thick if you remove the space bar). The GlideLok door child lock is an effective baby proofing, toddler proofing door latch and is also an alternative for door alarms for kids safety.