The Si4904DY from Vishay is a MOSFET with Continous Drain Current 8 A, Drain Source Resistance 13 to 19 milliohm, Drain Source Breakdown Voltage 40 V, Gate Source Voltage -20 to 16 V, Gate Source Threshold Voltage 0.8 to 2 V. Tags: Surface Mount. More details for Si4904DY can be seen below.