Triac thyristor, Bourns circuit protection, High current flow, Thyristor circuit

 TS820 Series 600 Vdrm 8 A Sensitive Silicon Controlled Rectifier SMT - TO-252

https://www.futureelectronics.com/p/electromechanical--circuit-protection--power-thyristors/ts820-600b-tr-stmicroelectronics-9096413