The Device is made of 2mm mild steel and powder coated in black.
It fits right or left handed sliding windows.
It can be permanently fitted by unscrewing the keep (the part attached to the window frame)
and placing the device between the keep and the window frame, as shown below and replacing the keep on top of the device, using the longer screws provided with your purchase.
If you are not into DIY you can just place the device behind the keep and close the window
as you hold it in place, then just pop the pin into the slots as shown. This will still do the same job, but you will have to hold it in position every time you open and close the window.