The GS66516B from GaN Systems is a GaN Power Transistor with Gate Threshold Voltage 1.1 to 2.6 V, Drain Source Voltage 650 V, Drain Source Resistance 25 to 65 milli-ohm, Continous Drain Current 47 to 60 A, Pulsed Drain Current 120 A. Tags: Die. More details for GS66516B can be seen below.