Got 4 of these a couple years back and using 3 to hold windows open. They mount to the mid point of the window / door frame and then put the stub at the point of contact on wall. I have all masonry walls and it holds good with just an expansion anchor drilled+glued in. Get the jewelers screwdriver kit to adjust the catch; I have had to tune up the door which is heavier a time or two. A little pricey but good quality and a great looking solution for rustic/country style.