The APT4F120S from Microchip Technology is a MOSFET with Continous Drain Current 4 A, Drain Source Resistance 4200 milliohm, Drain Source Breakdown Voltage 1200 V, Gate Source Voltage -30 to 30 V, Gate Source Threshold Voltage 2.5 to 5 V. Tags: Surface Mount. More details for APT4F120S can be seen below.