INSTALLATION - Our package includes 1pc door knob and 3pcs keys. This knob set can be used for left or right handed doors. DURABLE DESIGN - The sturdy construction of these door knobs allows them to be strong, durable, and long lasting. The knobs' sturdy design prevents breakages and breakages that can occur with lower quality mortise door knobs. The chrome finish adds a touch of elegance to your home or office. FUNCTION - The front door knobs feature a small rotary knob on one side to lock the door and a lock and key mechanism on the other side of the door. 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 optimal security. Specifications Material: Stainless Steel Color: Silver Dimensions (L x W): Approx. 170 x 75mm/6.7 x 2.95inch Center Distance: Approx. 60mm (Type A), 70mm (Type B) Suitable Door Thickness: About 35mm-45mm/1.4-1.77inch