The Sentry BSR10 Safety & Expansion Relay is designed for monitoring safety devices, such as emergency stops. It has 3 normally open (NO) relay outputs and 1 normally closed (NC) relay output. The relay operates on a +24 VDC supply voltage and features screw terminals for easy installation. This relay can be used directly in the voltage supply circuit of the relay to monitor safety devices, or it can be used as an expansion relay for a safety relay or safety PLC to increase the number of safe outputs.