No window is perfectly secure and unable to be broken into. That said, casement windows provide less ease of access for would-be intruders than other styles of window. If the intruder breaks a hole in the glass, unless it is large enough to fit through, they need to open the window. This involves turning the crank, which is hard to do through broken glass. For extra deterrence and to slow down a potential intruder, homeowners may remove the crank handles on some styles of casement windows and keep them unreachable from the outside but nearby for ease of use.