Defender Security S 4003 Zamak Twist-In Sliding Door Lock for Patio Sliding Door Systems and Horizontal Sliding Windows, 1-9/16 Inch Hole Spacing, Black, Set of 1

This inexpensive patio lock works perfectly for my patio door. I look at a whole bunch of other patio door locks that is expensive but did not fits on my door, and even purchase the Deerfield Sliding Glass Door Deadbolt Lock (Aluminum Frame - White) which I find was not secure and they can rattle and jiggle the door and it would come loose. I thought my high security front door locks were cracked by someone but it seems they crack the Deerfield patio lock instead.This lock is cheap and works like a charm. I could have gotten this at my local hardware store but not in black. It seems that black color for this lock is of low demand so I would have to special order. I decided to order it through Amazon with it's 2 days shipping instead of special ordering it at my local hardware store and wait 1-2 weeks.I am very happy with this lock and highly recommend it anyone who has a sliding patio door.If you want to see what the installation look like, see the Youtube video below[...]8/1/21016 UpdateIt might be better install this Prime-Line Products U 9861 Push-in Sliding Door Keyed Lock, Aluminum Finish with key locking function for extra security. The installation would be the same as the video link above. And the functionality would be the same except for key locking capability.

This gave easy, inexpensive added security to a patio door which has the sliding panel on the outside (because a wood stop wouldn’t work). It’s nice that it can be installed it in any number of positions. I chose the header near the stationary panel for strength and convenience (I didn’t want us to have to stoop down to the floor to operate it). I like that it rotates (about 1-1/2 or 2 full turns) to lock/unlock and stays where it’s set. The instructions are clear; just take care to fasten it close enough so the thin part of the pin goes nearly all the way into the adjacent rail.

Easy to Lock and unlock. I used this on a sliding door on a trailerable houseboat this prevents the door from opening on the road When in transit.

We needed a lock on our slider so the dogs could go in and out with the door secured with a small opening. This lock was easy to install and works perfectly.

I got two of these for my sliding doors. The trick to installing these is to install with as little wiggle room as possible when door is locked. If you leave too much wiggle room and you begin moving door back and forth trying to open the lock might give out. One of my locks lost the pin which holds the bolt together. I had to remove from door turn it around and fixed it by using a small screw instead of a pin for holding the bolt in. It works but it’s a little stiff turning the knob. Don’t know if I would buy these again.

I used this on a patio door as an extra layer of protection to keep kids from being able to go out that door by the pool (unless they can reach that high). I think the quality is great. It does take an extra second to screw it in rather than throwing a latch, but I prefer this as I think it's more secure.

Perfect product to secure a sliding glass door!

These are a great concept but the internal thread that advances the pin into the door breaks very easily. So they are easy to install and will hold the sliding door or window closed but don't twist the knob very hard or it will break.