Ball door lock designed for direct replacement of existing knob locks without drilling or modifying the door. Key benefits Easy retrofit: Installs in place of most existing ball knob locks using the same mounting holes. No drilling required. Reliable fallback options: Includes a mechanical key and a USB emergency power input for use when the lock is off or batteries are depleted. Automatic locking: Locks automatically after closing, reducing the risk of leaving the door unsecured. Long battery life: Operates on 4 AAA batteries with typical battery life up to 8 months under normal use, minimizing maintenance. Function and performance Primary operation is battery powered for normal daily use, with automatic locking behavior to simplify access control. Mechanical key override allows manual entry when electronic functions are unavailable. USB emergency power input provides temporary power to restore electronic operation without replacing batteries immediately. Designed for consistent, repeatable operation to support frequent use in homes and small commercial settings. Compatibility and size Fits most standard interior and exterior doors prepared for conventional ball knob locks, allowing direct replacement without altering door structure. Compact form factor designed to occupy the same footprint as common knob locks so trim and strike plates generally remain usable. Constructed for everyday use with durable materials suitable for door hardware; designed to integrate with existing door preparations. What is included Electronic ball door lock unit Mechanical key for manual override USB emergency power input provision Instructions for direct replacement installation Typical use scenarios Home entry and interior doors: an aging ball knob lock on an apartment or house door to gain automatic locking and electronic backup options while keeping existing door trim. Rental units and property management: Quick retrofits between tenants without drilling or door modifications, plus mechanical and USB backup options for staff access. Office and small business rooms: Upgrade meeting room or supply closet locks to automatic locking while maintaining a mechanical override for afterhours access. Installation notes Remove the existing ball knob following standard procedures and install the replacement unit into the existing bore and latch assembly. Follow the included instructions for battery installation, setup, and testing of the mechanical key and USB emergency power input. If door or latch dimensions differ from standard preparations, confirm fit before installation. This ball door lock is intended as a straightforward replacement solution that combines automatic locking convenience with mechanical and emergency power backups for reliable day to day use.