ABB 2TAZ312000R2041 is an electromagnetically operated mechanical latching relay from the E290 range, used in energy-saving lighting-control systems. Typical applications are private houses, factories, commercial and public buildings, and industrial plants where lighting must be operated from three or more locations. Each button press sends a short pulse to the coil, which mechanically latches the internal main contacts until the next control pulse arrives, in the same way as a ballpoint pen. The device is rated 16 A, coil 24 V AC / 12 V DC, with 1 NO contact and DIN-rail mounting.