This is a data sheet for a small signal transistor, model MPS4123/D, which is a NPN silicon transistor. Its maximum collector-emitter voltage is 30V, maximum collector-base voltage is 40V, maximum emitter-base voltage is 5.0V, maximum collector current is 200mA, and total power dissipation is 625mW. Its operating and storage temperature range is -55°C to +150°C.