This part is a kind of semiconductor called MRF581.

Function of this product has HIGH FREQUENCY TRANSISTOR.

Manufacturers : Motorola

Image and pinout :

Some of the text within the PDF file :

MRF580 MAXIMUM RATINGS Rating Symbol MRF581 MRF581 Unit Collector-Emitter Voltage vCEO 18 18 Vdc Collector-Base Voltage vCBO 36 36 Vdc Emitter-Base Voltage Collector Current Continuous vEBO "C 2.5 200 2.5 Vdc 200 mAdc Total Device Dissipation @TC = 50°C(1) Derate above Tq = 50°C PD 2.5 2.5 Watts 25 25 mW/°C Operating and Storage Junction Temperature Range TJ. Tstg -65 to + 150 -65 to + 150 °C (1) Case temperature measured on collector lead immediately adjacent to body of package. CASE 317A-01, STYLE 2 HIGH FREQUENCY TRANSISTOR NPN SILICON MRF581 CASE 317-01, STYLE 2 HIGH FREQUENCY TRANSISTOR NPN SILICON ELECTRICAL CHARACTERISTICS (TA = 25°C unless otherwise noted.) OFF CHARACTERISTICS Characteristic Collector-Emitter Breakdown Voltage OC = 1.0 mAdc, Bl [ ... ]

MRF581 PDF Datasheet Download