The SiA421DJ from Vishay is a MOSFET with Continous Drain Current 12 A, Drain Source Resistance 29 to 56 Milliohm, Drain Source Breakdown Voltage -30 V, Gate Source Voltage -20 to 20 V, Gate Source Threshold Voltage -3 to -1.5 V. Tags: Surface Mount. More details for SiA421DJ can be seen below.