The STS521120U351AH from Eaton is a Power Diode with Reverse Current 1.0 µA, Reverse Voltage 12 V, Temperature operating range -55 to 150 Degree C, Reverse Breakdown Voltage 13.3 V, Total Capacitance 35 to 40 pF. Tags: Surface Mount. More details for STS521120U351AH can be seen below.