The TK55S10N1 from Toshiba is a MOSFET with Continous Drain Current 55 A, Drain Source Resistance 5.5 to 6.5 Milliohm, Drain Source Breakdown Voltage 100 V, Gate Source Voltage -20 to 20 V, Gate Source Threshold Voltage 2 to 4 V. Tags: Surface Mount. More details for TK55S10N1 can be seen below.