The MMBT3904-MS with SOT-23 is a Bipolar Transistors - BJT ROHS manufactured by MSKSEMI. This transistor is a type of n-p-n device based on a three-layer structure of two p-type semiconductor material, known as "base" and "collector" layers, and one n-type semiconductor material, referred to as the "emitter" layer. The device allows a low-power current to flow between the collector and emitter terminals when a voltage is applied to the base terminal. It is available in the SOT-23 package format, which is a small, three-pin device designed for surface-mount applications. This transistor is compatible with RoHS production processes and is suitable for use in a variety of applications including digital circuits, analog circuits, and amplify signals.