The DoorJammer provides dependable privacy and security in a compact, portable package. Using an ingenious system of hinges and angles, it converts any external, horizontal force on a door into vertical, interior force, which, in turn, anchors the DoorJammer firmly onto the ground – preventing entry, even when the door latch is broken. Simply pull the DoorJammer upward to release it from its locked position. It can be installed on flat or inclined floor surfaces of any type: hardwood, carpet, tile, linoleum, concrete, etc. We include a velvet travel bag, so you can take it with you everywhere.