The Von Duprin 900-4RL is a versatile relay distribution power supply board designed to enhance security systems. This 4-relay board integrates logic for managing security interlocks, automatic operators, and timed delays. It supports a universal 120-240 VAC fused primary input and features a battery backup board that automatically selects voltage. The board monitors both AC input and DC output, with LED indicators for easy status checks. An optional fire alarm emergency interface relay is also available. Its externally visible AC input indicator comes with isolated SPDT contacts. Upgrade your security setup with this reliable and efficient power supply board today!