The DH-DS21 Wireless Chime is an indoor standalone doorbell that rings when your outdoor video doorbell is pressed. The DH-DS21 can be paired with Dahua's LincX2PRO DHI-DB11 or DH-DB6I doorbells. With the DMSS application, you can customize your chimes, making your security system not only functional but also personalized. For added convenience, the DH-DS21 Wireless Chime can be linked to multiple video doorbells at the same time, ensuring you never miss a visitor no matter where you are in your home.