This part is a kind of semiconductor called 2N4170.

Function of this product has SILICON CONTROLLED RECTIFIERS.

Manufacturers : Digitron Semiconductors

Image and pinout :

Some of the text within the PDF file :

2N4167-2N4174 High-reliability discrete products and engineering services since 1977 SILICON CONTROLLED RECTIFIERS FEATURES  Available as “HR” (high reliability) screened per MIL-PRF-19500, JANTX level. Add “HR” suffix to base part number.  Available as non-RoHS (Sn/Pb plating), standard, and as RoHS by adding “-PBF” suffix. MAXIMUM RATINGS Rating Peak repetitive forward and reverse blocking voltage 2N4167 2N4168 2N4169 2N4170 2N4172 2N4174 Forward current RMS Peak forward surge current (one cycle, 60Hz, TJ = -40 to +100°C) Circuit fusing (t = 8.3ms) Peak gate power Average gate power Peak gate current Peak gate voltage Operating temperature range Storage temperature range Stud torque Symbol VDRM, VRRM IT(RMS) ITSM I2t PGM PG(AV) IGM VGM TJ Tstg Value 25 [ ... ]

2N4170 PDF Datasheet Download