Bests & Worsts Reviews from Amazon

I put these on the bedroom windows in my kids' rooms. I put 2 on each window (1 on each side). I leave about 3 inches so air can flow, but no one can get in. Better than putting bars on windows since bars cannot be removed in case of emergency/fire. I feel so much safer going to sleep and knowing my kids will be there in the morning and no one can get in. I have purchased several more at this point. Here is some helpful info: I use them on double-hung windows myself. So, if you look at the picture of the little lock, you can see a square on top, a turning knob up front, and tucked behind is a piece that moves forward and backward. You take the lock and open that sliding portion by turning the knob. You open it up big enough to slide the "teeth" of the lock onto the window frame. (See pics) This can attach to any frame as long as the frame is thin enough to fit in the teeth. The teeth open about 1/2", so if the frame you want to attach to is 1/2" thick or thinner/smaller, then you are good to go. Slide it onto the frame (see pic) and turn knob to tighten. Once you have it good and tight, you push the knob flat and that will secure it even more. Note - make sure to use BOTH locks on a single window. In testing, I placed one lock in a way that it would allow the window to open 3-5 inches. I then "pretended" I was trying to get in and took the window from the bottom and shoved it up pretty hard. I did this a few times, and there is enough wiggle by going up and down with the window that I can slowly, but loudly, get the lock to inch up until there is enough room for me to climb into the window. However, it is really hard to do that when BOTH locks are used on either side of the window. Having two in place is a pretty secure situation. I also like that I don't have to screw these into anything, which not only damages the window frame but also allows for only one position. These allow you to move them up and down at anytime, or just remove them. Meaning, you can place them in a way to allow the window to open 3" or 4" or almost all the way open, or almost all the way closed, wherever you want, and you can change it from day to day if you like. Nothing permanent. I love these! Sorry about some of the pics. Amazon would not allow me to flip a couple of them. Hope it still helps.