1.) What types of doors can the Secure Lock be used on?
The Secure Lock (SL) is used for single hung doors. It is applied to the doorjamb itself and uses the strength of the studs surrounding the door as, well as the carbon steel, to make the door very difficult to kick-in. The SL can also be installed on door with sidelights. There is no place for the SL to be applied on any double hung a door.