BC817-40.215 is a NPN transistor manufactured by Nexperia, specifically designed for use in switching and amplifying applications. It has a breakdown voltage rating of 40V, a maximum collector current rating of 800mA, and a maximum power dissipation rating of 625mW. It also features a high current gain, a low noise figure, and excellent switching speed. This transistor is useful in a wide range of applications including amplifiers, switching circuits, and voltage regulators.