Viper - Indoor Wireless Bidirectional Siren 504s for Home DIY Security System Compatible with Viper home monitoring and security system starter kits For use with your existing system. 128-bit AES encryption Helps ensure safe, secure use. Battery-powered (requires 4 AA alkaline batteries, not included) Emits a loud sound up to 85dBA for up to 90 seconds following an intrusion To help deter potential intruders and warn people in your home of a security event. For easy wireless operation. Up to 2 years of battery life ensures long-lasting use. Can also function as a doorbell For multipurpose use. Tamper alarm Notifies you if someone tries to remove the siren from its back bracket.