Review on Sumnacon 2 Pcs Door Flush Bolts - 6 Inch Concealed Security Locks for French, Composite, Wood, Double, Dummy Doors - Brush Stainless Steel Finish by George Robinson

My old double leaf door had locks that slide up/down to slide the deadbolt into the hole. The one at the top of the door sometimes started sliding down due to gravity when the main door opened/closed and vibrated. I kept checking to make sure it stayed locked. I bought these as they were the same apparent dimensions as the old ones and figured they would be a fairly quick replacement. Of course, after removing the old locks, I found that they didn't cut through the entire area in the side of the door. In other words, the old ones were cheap and unreliable blocks. So I had to take a little time hollowing out a pocket to install it. These are great upgrades, but be prepared to do a little work if you're upgrading an old door. A sharp set of chisels and maybe a Multimax tool to speed things up. I also had to widen the existing top/bottom holes in the door frame a bit as the bolt alignment wasn't quite the same, but at least it was easier to do. Bolts and I don't have to worry about them opening themselves and it's safer as you can't bypass them with a wire or anything from the outside. You can only open/close them when the main door is open. They are also much sturdier than the old set. The latch seems to be of a higher quality, and a solid, solid body built into the door leads me to believe it will hold up better if someone tries to knock it out.