Video Doorbell S220 Add-on 2.5x the Clarity: The built-in Sony 2K sensor and professional-grade lens allow you to view activity in picture-perfect resolution. See visitors in sharp detail as they approach your door. Dual Power Options: Half a year of coverage from one charge or non-stop power supply via a wired connection. Entry Sensor 2-YEAR BATTERY LIFE: One CR-123A battery provides monitoring for 730 days. FOR DOORS AND WINDOWS: Small and compact design fits onto any door or window frame.