SL-500 Outdoor Bell Box - highly resistant PC housing, UV prevention - twin piezo sounders with 120db at 1m, - single piezo sounder is optional - SAB/SCB function available - positive/negative siren trigger - positive/negative strobe trigger - battery backup - lens colors in red, blue, orange, white - two way tamper switch protection - LED diagnosis indication outdoor siren, outdoor alarm siren, siren alarms, outdoor bell box, outdoor sounder, external sounder, external siren, garden siren, battery backup siren, siren with strobe, siren with flash, siren with flasher, siren for alarm systems, burglar alarm sirens, intruder alarm sirens, security siren, safety siren, emergency siren, siren horn, siren speaker, alarm and siren, sirens for burglarproof, sirens for anti intrusion, sirens for home security, sirens for residential security, sirens for business security