The MRRN2B-12D is a type of and part of the Struthers-Dunn product line. It is a 12A, 120-240VAC Non-Latching Relay, which is a type of electromechanical device used to control electrical circuits remotely. The MRRN2B-12D can be used in a variety of applications, including motor and compressor control, ambient air conditioner control, lighting systems, and more. It features 12A contact capacity, a trip-free design, and comes with a built-in socket for easy mounting.