The FS55MR12W1M1H_B11 from Infineon Technologies is a MOSFET with Continous Drain Current 15 A, Drain Source Resistance 52.9 to 114 milliohm, Drain Source Breakdown Voltage 1200 V, Gate Source Voltage -10 to 23 V, Gate Source Threshold Voltage 3.45 to 5.15 V. Tags: Chassis Mount. More details for FS55MR12W1M1H_B11 can be seen below.