The Si4166DY from Vishay is a MOSFET with Continous Drain Current 30.5 A, Drain Source Resistance 3.2 to 5.5 milliohm, Drain Source Breakdown Voltage 30 V, Gate Source Voltage -20 to 20 V, Gate Source Threshold Voltage 1.2 to 2. V. Tags: Surface Mount. More details for Si4166DY can be seen below.