The BSS138K from First Silicon is a MOSFET with Continous Drain Current 0.3 to 0.16 A, Drain Source Resistance 1.3 to 2.5 ohm, Drain Source Breakdown Voltage 55 V, Gate Source Voltage -20 to 20 V, Gate Source Threshold Voltage 0.8 to 1.5 V. Tags: Surface Mount. More details for BSS138K can be seen below.