The SIEMENS 3TH2040-0BB4 is a highly reliable SIRIUS contactor relay designed for switching control and auxiliary circuits in demanding industrial environments. This compact S00 size relay features four normally open (4NO) contacts and is operated by a 24V DC control supply voltage. It is engineered for durability and consistent performance, offering secure connections via its screw-type terminals. The device can be easily installed using either screw mounting or by snapping it onto a standard 35 mm DIN rail, providing flexibility for various panel layouts. It is an essential component for automation and control systems where dependable signal switching is critical.