When sourcing electric sirens, the most critical factor is the Sound Pressure Level (SPL), typically measured in decibels (dB). For industrial environments, look for units providing 110dB to 130dB at a 1-meter distance to ensure audibility over ambient noise. Additionally, verify the Effective Range, which can span from 500 meters to over 5 kilometers for high-power motor-driven models. Ensure the Motor Power (kW) and Rotation Speed (RPM) align with your coverage requirements, as higher RPMs generally produce more piercing, high-frequency tones.