Magnum ES42 Series Hardened Edge Switch configured for industrial Ethernet applications. It is designed for harsh environments such as factory floors and utility sites, featuring an internal -48VDC power supply and a specialized terminal block for alarm monitoring - Power Input: Internal -48VDC supply with an operational range of 30V to 60V DC. Alarm Relay: The "TR" suffix typically indicates a Terminal block with Relay contact, used to monitor internal power-sense status. Temperature Rating: Hardened ("H") models are rated for operating temperatures between -25°C to +60°C (-13°F to 140°F) per UL 60950 standards. Enclosure: Robust aluminum sheet metal designed for convection cooling without the need for internal fans, making it resistant to dust and moisture. Dimensions: 3.6 in H x 3.0 in W x 1.7 in D