The FS03MR12A6MA1LB from Infineon Technologies is a MOSFET with Continous Drain Current 400 A, Drain Source Resistance 2.75 to 4.55 milliohm, Drain Source Breakdown Voltage 1200 V, Gate Source Voltage -10 to 20 V, Gate Source Threshold Voltage 3.25 to 5.55 V. Tags: Chassis Mount. More details for FS03MR12A6MA1LB can be seen below.