Surge protection, Triac thyristor, high current flow, Light control, Thermistors

 TN2540 Series 800 V 25 A Surface Mount Standard SCRs - D2PAK

https://www.futureelectronics.com/p/electromechanical--circuit-protection--protection-thyristors/tn2540-800g-tr-stmicroelectronics-5021390