This flush bolt features a strong spring mechanism and can be used on sliding/folding door systems. Maximum depth of cut out: 18mm. Usually used to secure the slave door, it requires rebating into the surface or edge of your door. Overall Size: 306mm x 21mm Return Length: 20mm Receiver Plate: 35mm x 20mm x 3mm Shoot Bolt Diameter: 9mm Maximum Cut Out Depth: 18mm