FUNCTION: The front door handles feature a small turn knob on one side to lock the door and a lock and key mechanism on the other side of the door. Front door knobs are used for interior or exterior doors that require additional security. The door can be locked and unlocked from the outside using the key or from the inside using the snib function. DURABLE DESIGN: The sturdy construction of these door handles allows them to be strong, sturdy and durable. The sturdy design of the knobs prevents slamming and breaking that can occur with inferior mortise door knobs. The chrome finish adds an elegant touch to your home or office. SECURITY: These chrome door knobs provide additional security with the lock and key mechanism. They are ideal for home offices, bedrooms and interior porch doors as they provide optimum security. APPLICATION: These door locks can be used on interior or exterior doors with a thickness of 35mm to 45mm. The tubular latch is adjustable to 60mm or 70mm (the distance