This part is a kind of semiconductor called SM24.

Function of this product has TVSarray Series.

Manufacturers : Microsemi Corporation

Image and pinout :

Some of the text within the PDF file :

SM03 8700 E. Thomas Road Scottsdale, AZ 85251 Tel: (480) 941-6300 Fax: (480) 947-1503 thru SM36 TVSarray™ Series DESCRIPTION (500 watt) This 3 pin Transient Voltage Suppresor offers 2 unidirectional or 1 bidirectional protection at the board level from voltage transients caused by electrostatic discharge (ESD) as defined by IEC 1000-4-2, electrical fast transients (EFT) per IEC 1000-4-4. Unidirectional protection, can be accomplished by connecting the Input/Output lines to pins 1 and 2 and pin 3 to common or ground. In a bidirectional configuration pin 1 or pin 2 is connected to the Input/Output line while the opposite pin is connected to common or ground. Pin 3 is not connected. The SM03 thru SM36 product provides board level protection from static electricity and other induced volta [ ... ]

SM24 PDF Datasheet Download