Struthers-Dunn is a manufacturer of industrial control products headquartered in Waverly, Pennsylvania. Their product line includes relays, timers, contactors, and other electromechanical control products. The 40051 part is a line of air interposing relays. These relays feature a hermetically sealed enclosure and are designed to handle a wide range of system control requirements including applications with special environmental needs such as hazardous locations. The 40051 is a versatile relay for various air circuit control tasks such as AC/DC voltages, current control, voltage sensing, and contact status monitoring. It is an ideal component for applications with space or power restrictions. Other features include a 2-pole single-throw relay, SPDT form-C contacts, and shock and vibration resistors.