Prime-Line S 4033 Aluminum Tamper Resistant Sliding Window Lock, Fits 1/4 inch Track, Black, 2 Pack

The fact that a hex key is required to remove these (if they are installed properly on a place where they fit) makes them significantly superior to the more common ones that have thumbscrews and require no tool.I have old sliding aluminum windows (early 1960s vintage.) My security measures are:- 7/8" diameter wooden dowels cut to exact length to keep the sliding panes closed,- Sheet metal screws set in the frame above the sliding panes to prevent them from being lifted out (they are designed to come out for cleaning,)- Sash locks (this product). I use TWO on each window to make them even more vexing.A burglar would have to break glass to get in, and it wouldn't be as simple as breaking glass then removing the wooden dowel.I have ordered some Doberman Security brand stick-on window alarms to add another layer of deterrence to the most vulnerable windows.Eventually I plan to replace all of the windows with double- or triple-pane break-resistant ones. But that will cost some serious money.

Works like a charm. 100% recommended.

Very easy to install with provided tool. It not only prevents opening (sliding) the window from the outside, but it also allowed me to keep it tightly closed again the weather and insulation neoprene strip on the sides of the window frame.

I had earlier purchased some that were silver, but the black blends much better with our bronze window frames. I like that they have an Allen key fastener. It's very solid, but secure too. Each 2-pack comes with an Allen key.

These are great we purchased a second set. Perfect for toddlers or older children who like to wander. If you do not have the Allen wrench it will not come off.

Work great to limit the travel of window for pool boundary.

These work well for their purpose. Easy to install and remove - no marks left. We used these in a room with a glass break sensor and so far so good. Great color looks just like the photo.

Used it for my window to keep the top window from being pulled down. Also, used some of the "screw" type that can be easily removed by anyone from the inside without a tool.No one is breaking in my apartment without actually breaking a window...