The powerful Smart Lock SX-33 is an intelligent door lock designed to fit into the cylinder of your front door. With an internal size of 30 to 35 millimeters and an external size of 30 to 45 millimeters, the SX-33 fits all cylinders. The lock connects wirelessly to your smartphone via Bluetooth, allowing you to open the door hands-free or with the push of a button when you are near the front door. You must first be at least 200 meters away from the door. If you do not have your phone with you, you can still open the door by entering your set pin code using the rotary knob on the lock. This ensures you can always gain entry. The Smart Lock can be installed within a few minutes and operates on batteries with a lifespan of approximately 2 years.