This part is a kind of semiconductor called 2N4948.

Function of this product has PN UNIJUNCTION TRANSISTORS.

Manufacturers : Digitron Semiconductors

Image and pinout :

Some of the text within the PDF file :

2N4948, 2N4949 High-reliability discrete products and engineering services since 1977 PN UNIJUNCTION TRANSISTORS 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 Symbol Value Unit RMS power dissipation(1) PD 360 mW RMS emitter current Peak pulse emitter current(2) Ie 50 mA ie 1.0 Amp Emitter reverse voltage VB2E 30 Volts Storage temperature range Tstg -65 to 200 °C Note 1: Derate 2.4mW/°C increase in ambient temperature. Total power dissipation must be limited by external circuitry. Interbase voltage limited by power dissipation: V B2B1 = √(RBB*PD) Note 2: Capacitance [ ... ]

2N4948 PDF Datasheet Download