FUNCTION: The door handles have a small turn button on one side for internal door locking and a safety release function on the other side. The door can be locked and unlocked from the inside with a simple turn of a knob. They are used for interior doors to combine security and privacy. DURABLE DESIGN: The robust construction of these door handles makes them strong, sturdy, and durable. The robust handle design prevents rattling and breakage that can occur with inferior spindle door handles. The polished brass finish adds a touch of elegance to your home or office. SECURITY: These polished brass door knobs have a safety feature on the exterior door knob. By using the included override key, the door can be unlocked quickly and safely from the outside in an emergency. These safety knobs are not intended for use with standard lock and unlock keys. USE: These door locks can be used on interior doors with a thickness of 35 mm to 45 mm. The tubular latch is adjustable to 60 mm or 70 mm (the distance between the center of the hole and the edge of the door). They are suitable for both commercial and private applications. INSTALLATION: These chrome door handles come with mounting instructions and templates for easy installation. All fixings and accessories are supplied with color-matched screws, tubular latch, and override key. This set of knobs can be used for left or right-hand doors.