Ball catches are generally used on doors, but can be used in other applications. The way they work is simple: on the top of the door there is a hole drilled and a spring loaded ball is installed which slightly protrudes from the top of the door. On the jamb above a strike plate is installed much like a strike plate used on a regular door, but this strike has a small indentation to fit the contour of the ball rather than a hole for the latch. As the door shuts, the spring loaded ball rests in the indentation on the strike and keeps the door closed. Length: 1 5/16" Width: 1 1/8" Projection: 1/2"