The 1SMAZ5931B is a type of 1.5W 18V SMA Zener diode manufactured by the Chinese company Good-Ark. This device is a surface-mount set of semiconductor diodes designed to control the flow of electricity in applications that require tight tolerance regulation. It has an operating temperature range from -55 to +175°C, a maximum power dissipation of 1.2 Watts, and a maximum zener voltage of 18V. The device is RoHS compliant, which means that it is held to the strictest standards of material-has and environmental-friendliness. It is also Lead-free, making it safe to work with.