Swing in doors. Flat frames, same plane as the door. First, go to the hardware store and get some quality steel, #8 Phillips, good brand, flat head wood screws, I needed 2 inch for my door frame.

You need some space between the door and the frame for the tongue of this lock. If no space you'll need to mortise it out with a wood chisel. Look before ordering.

If space, about 1/16 to 3/32. With door and this lock closed, slide it in the crack between door and frame and mark with a pencil on the door side with an eye to mount later in same position.

Open lock, open door, holding lock in place. Mark slotted hole with Phillips screw, you need a screwdriver, or reversible portable drill with P2 bit preferable.

Hold and match pencil mark to eyeball mark if it moved much. Or do over.

Install a wood screw in slotted hole in center just right enough to allow later adjustment, screw it in to just loosely snug but movable a little.

Flip lock lever back, close door, flip lock into locked position and make sure it snaps into place easily. Adjust as necessary for easy fit and use and that it's locked in position.

Make sure it doesn't move, open door, tighten center slot screw, insert and install other screws.

Ours is extremely low use door, with original 1980 crappy lock. The wind can blow it open.

If this holds up and the springs don't break, shouldn't, we don't open the door. Many reviews claim crappy springs across various brands of this same device and that they fail with use. If failure, I'll be back to downgrade review considerably.

DO NOT INSTALL ON A DOOR THAT IS USED FOR AN EMERGENCY ESCAPE ROUTE OR LOCK YOURSELF OUT WITH THIS SIMPLE 🔠GADGET. IF SPRINGS FAIL, YOU'RE TRAPPED.âŒðŸ§¯ðŸ”¥ðŸ¥µâš«

10 minutes to install with proper tools.

These were easy to install and work great. They do not mark the door and hold tight so the door doesn't open. It took me a few tries to figure out how to release them, but once I figured out that it is spring loaded and needs to be pulled horizontally toward the door, it was all good.

Also, when my kids are older I will probably remove them and am happy that they install inside the jam rather than on top of the trim like other safety latches. No one will ever know they were there once I remove them.

This is the 4th lock on my door of my house and it's so easy to install and it's better than alot of home security gadgets I've bought over the years. I can't believe this lock is as perfectly priced and I got 2 of them. They work so very well on my doors.

The way this item is designed is pretty good. The included bolts penetrate pretty deep into the door jamb and give added support to the deadbolt when place properly. For example, you wouldn't want the deadbolt and this item to be right on top of each other. That section of the door jamb would be taking the brunt of the force to break in and probably wouldn't hold up very long. But if you install this item or even two, spaced evenly on the deadbolt side of the door jamb, you've essentially made the door have 4 or 6 reinforced points, depending if you have 2 or 3 hinges, and as long as the doorjamb is solid, the door pretty much becomes part of the wall. This item is much better than any type of slide latch.

My wife made me order these for our front door and I am glad I did. Now she feels a lot safer when I'm not home and she is by herself. These are very sturdy, easy to install and well made. It would take a lot to kick a door in using these....