advantage is the fact that the system is simple to install in a window opening for example there are only three major steps in installing the device namely 1 installing the vertical bars 31 into the openings in the horizontal crossbars 21 2 inserting the legs 36 of a pair of brackets 35 into opposite ends of a respective crossbar and 3 securing the other legs 37 of the brackets by the one way screws 39 to opposite sides 12 and 13 of the window frame in addition there are only four different parts that are required to complete the system namely the vertical bars 31 the horizontal crossbars 21 the right angular brackets 35 and the one way screws 39 thus this system may be produced in the form of kits which are ready to be inserted into a window opening with a minimum of tools for example a screw driver and a drill because the device is quick and easy to install it requires few tools and it permits an ordinary homeowner who has no knowledge of carpentry to install the security system in household windows while bars 31 have been described as the vertical bars and bars 21 as the horizontal or crossbars it will be apparent that if desired the bars 31 could be mounted horizontally across the window opening in which case bars 21 would extend vertically and would be fastened by brackets 35 to the header 14 and sill 15 respectively also although the brackets are shown to have flat legs 37 and 36 the exact shape of the legs could be modified without.